Light-shielding film, optical element and electronic device

Abstract

A light-shielding film (10), an optical element and an electronic device. The light-shielding film (10) is configured to be arranged on the surface of a transparent substrate (20), and the light-shielding film (10) comprises a matching layer (11) and a light-absorbing layer (12) which are stacked, wherein the matching layer (11) is configured to be connected to the transparent substrate (20), the matching layer (11) has a refractive index Nm greater than a refractive index Na of the light-absorbing layer (12), and a value of the refractive index Nm of the matching layer (11) ranges from 0.85 Ns to 1.03 Ns, wherein Ns is the refractive index of the transparent substrate (20). The light-shielding film (10) can be used on a glass surface having a high refractive index, so as to reduce the reflectivity of the light-shielding film (10) and reduce the problems of stray light and ghost images.

Description

Light shielding film and optical element and electronic device

[0001] Cross-reference to Related Applications

[0002] This application claims priority to the Chinese Patent Application No. 202411036294.3, filed on July 30, 2024, entitled "Light shielding film and optical element and electronic device", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of light shielding materials, in particular to a light shielding film and an optical element and an electronic device. BACKGROUND

[0004] The light shielding film can be widely applied in the photographic module of a camera, a backlight module of an LCD or other electronic devices, for blocking external light. An ideal light shielding film should completely absorb external light and achieve zero reflection. However, in the prior art, the light shielding film usually adopts black ink to realize light absorption and reduce reflectivity by relying on the light absorption of the black ink layer. In an optical element, the light shielding film is usually arranged on the surface of a transparent substrate such as glass. For a glass with a high refractive index, such as a refractive index greater than 1.84, due to the low refractive index of the existing ink, which is usually less than 1.65, such as 1.63, reflection will occur at the interface between the glass and the ink due to the large difference in refractive index, causing stray light and ghosting, and thus affecting the light filtering or imaging effect. SUMMARY

[0005] The present application provides a light shielding film and an optical element and an electronic device, which reduces the reflectivity of the light shielding film for a glass with a high refractive index, and reduces the problems of stray light and ghosting.

[0006] In a first aspect, the present application provides a light shielding film, which is arranged on the surface of a transparent substrate. The light shielding film comprises a matching layer and a light absorbing layer, and the matching layer and the light absorbing layer are arranged in a stack. The matching layer is used to connect with the transparent substrate. The refractive index Nm of the matching layer is greater than the refractive index Na of the light absorbing layer, and the refractive index Nm of the matching layer is in the range of 0.85Ns to 1.03Ns, where Ns is the refractive index of the transparent substrate.

[0007] The light shielding film of the present application comprises a matching layer with high refractive index and a light absorbing layer with relatively low refractive index. When combined with a transparent substrate with high refractive index, the refractive index of the matching layer Nm is 0.85-1.03 times the refractive index of the transparent substrate Ns, and after being combined with the transparent substrate, the refractive indices of the two are close to each other, which can reduce the reflected light between the transparent substrate and the matching layer, increase the transmitted light from the transparent substrate to the matching layer, and then the light absorbing layer can absorb the remaining light. In the light shielding film, the matching layer is used to be combined with the transparent substrate, so when the light shielding film is prepared, the matching layer is mainly provided with high refractive index to reduce the refractive index difference between the matching layer and the transparent substrate, and to reduce the problems of stray light and ghosting. The light absorbing layer mainly absorbs light, and its refractive index can be lower than that of the matching layer to achieve high light shielding effect.

[0008] In an optional implementation, the refractive index Nm of the matching layer is in the range of 0.985Ns-1.02Ns. When the refractive index of the matching layer satisfies 0.985Ns-1.02Ns, the matching degree of the refractive indices between the matching layer and the transparent substrate can be further improved, the reflectivity at the interface between the two can be reduced, the transmittance from the transparent substrate to the matching layer can be increased, and the problems of stray light and ghosting can be further reduced.

[0009] In an optional implementation, the extinction coefficient of the matching layer in the 400-700 nm wave band is greater than or equal to 0.0017 μm -1 and less than 0.03 μm -1 . Since the light shielding film is a multi-layer film structure, the matching layer and the light absorbing layer can realize different functions. Compared with a single-layer film structure light shielding film, such as a single-layer ink light shielding film, the matching layer can be made of a material with a lower extinction coefficient to increase the selection range of the material and reduce the manufacturing difficulty of the matching layer. At the same time, the matching layer with the above-mentioned extinction coefficient can also reduce the reflectivity between the light shielding film and the light-transmitting substrate, and reduce stray light.

[0010] In an optional implementation, the extinction coefficient of the matching layer in the 400-700 nm wave band is 0.0017-0.025 μm -1 . When the extinction coefficient of the matching layer is 0.0017-0.025 μm -1 , the matching layer and the transparent substrate can further eliminate stray light between the light shielding film and the transparent substrate.

[0011] In an optional implementation, the light absorption coefficient of the matching layer in the 400-700 nm wave band is 0.3-0.5 μm -1The matching layer mainly has high refractive index, and thus has relatively low light absorption coefficient. However, compared with the transparent substrate, the light absorption of the matching layer is much greater than that of the transparent substrate. When the light absorption coefficient of the matching layer is 0.3-0.5, the light absorption effect of the light shielding film as a whole can be improved.

[0012] In an optional implementation, the matching layer has a thickness of 5-20 μm, such as 5-15 μm, or 5-10 μm. Since the matching layer needs to have high refractive index, a large amount of high-refractive material needs to be added in the preparation process. If the thickness is too large, the adhesion of the light shielding film can be reduced, and the stability of the matching layer can also be reduced. Therefore, the thickness of the matching layer is set to be relatively small, so that the matching layer has high refractive index and high reliability.

[0013] In an optional implementation, the light absorption layer has a light absorption coefficient of 0.3-0.7 μm in the 400-700 nm wavelength range. -1 The light absorption layer mainly has light absorption effect in the light shielding film. When the light absorption coefficient of the light absorption layer is 0.3-0.7, the light absorption effect can be improved.

[0014] In an optional implementation, the light absorption layer has a thickness of 10-100 μm, such as 10-80 μm, or 10-40 μm. Since the refractive index of the light absorption layer is relatively low, the thickness of the light absorption layer can be relatively large, so that the light shielding effect of the light shielding layer can be improved.

[0015] In an optional implementation, the light absorption layer has a refractive index of 1.5-1.7. The refractive index of the light absorption layer is in the above range, so that the light shielding film can have basic refractive index requirements. In addition, the light absorption layer with the above refractive index has a wide range of material selection, and the performance of the material is stable. The light absorption layer with a relatively large thickness can be prepared, so that the light absorption effect can be improved, the transmission can be reduced, and the reliability of the light absorption layer can be improved.

[0016] In an optional implementation, the material of the matching layer includes resin, inorganic filler, and pigment. In the matching layer, the volume percentage of the resin is 10-98%, the volume percentage of the inorganic filler is 0.1-60%, and the volume percentage of the pigment is 0.01-30%. In the material of the matching layer, the inorganic filler is a high-refractive inorganic material, which mainly improves the refractive index of the matching layer. In the above components, the inorganic filler has a relatively high percentage, so that the high-refractive requirement of the matching layer can be met.

[0017] In a second aspect, the application provides an optical element, which includes a transparent substrate and the light shielding film of the application arranged on the surface of the transparent substrate. The matching layer is arranged between the transparent substrate and the light absorption layer and connected with the transparent substrate. The refractive index Ns of the transparent substrate is greater than 1.7, and the reflectivity of the optical element is less than 1%.

[0018] The optical element of the present application can adapt to the development of ultra-thin optical elements due to the refractive index of the transparent substrate being greater than 1.7. The light shielding film of the first aspect of the present application is arranged on the surface of the transparent substrate with high refractive index. The light shielding film is combined with the transparent substrate with high refractive index, and the low reflection of incident light is realized by using the light shielding film, so that the optical element with high refractive index and low reflection is obtained.

[0019] In a third aspect, the present application provides an electronic device comprising the optical element of the present application.

[0020] The technical effects achieved by the third aspect can be described with reference to the corresponding effects described in the second aspect above, which will not be repeated here.

[0021] The electronic device of the present application may, for example, include mobile devices such as mobile phones, computers, watches, etc., and also devices such as display screens with backlight display modules.

[0022] In the above possible implementation manners of the present application, the data such as the extinction coefficient of the light shielding film, the thickness of the matching layer, the light absorption coefficient of the matching layer, the thickness of the light absorption layer, and the light absorption coefficient of the light absorption layer, etc. should be understood as being within the scope defined by the present application within the range of engineering measurement error. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 is a structural schematic diagram of a light shielding film according to an embodiment of the present application;

[0024] Fig. 2 is a structural schematic diagram of an optical element according to an embodiment of the present application;

[0025] Fig. 3 is a schematic diagram of the transmission path of light in an optical element according to an embodiment of the present application;

[0026] Fig. 4 is a reflectivity test diagram of an optical element with different thickness matching layers.

[0027] Reference signs: 10-light shielding film; 11-matching layer; 12-light absorption layer; 20-transparent substrate. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings.

[0029] The terminology used in the following description merely to convey the particular embodiments and is not intended to limit the application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0030] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. Thus, the appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in additional embodiments," and the like in various places throughout this specification are not necessarily referring to the same embodiment, unless otherwise expressly specified. The terms "including," "containing," "having," and variations thereof are meant to encompass the terms "including," "containing," "having," and variations thereof, unless otherwise expressly specified.

[0031] The existing light shielding film is generally a single layer film structure, which is mainly formed by black ink, and can also be prepared by resin. When the single layer light shielding film is prepared by black ink, due to the material limitation, the refractive index of the black ink is generally below 1.65, and when combined with a glass substrate with high refractive index, due to the large difference in refractive index between the black ink and the glass substrate, reflection will occur at the interface between the two, resulting in stray light and ghosting, which affects the filtering and imaging effect. In addition, when the light shielding film is formed by resin material, in order to obtain a resin compound with high refractive index (greater than 1.8), a large amount of inorganic filler with high refractive index needs to be added to the resin. When a thick film is made of such resin material, due to the uniformity of the dispersion of the inorganic filler and the stability of the high refractive index resin material, it is difficult to obtain a light shielding film with a thickness of more than 10 μm and stable performance. In addition, when a thin film with a thickness of less than 5 μm is used to produce a high refractive index light shielding film with sufficient light shielding performance, the content of inorganic fillers, dyes and pigments added to the resin will be large, which will reduce the uniformity of the dispersion of the additives and the adhesion of the resin to the substrate, and it is difficult to obtain a light shielding film with high stability.

[0032] To solve the above problems, the application provides a light shielding film. The light shielding film of the application can include a two-layer structure, i.e. a light absorbing layer and a matching layer. The matching layer is used to contact the transparent substrate and is located between the transparent substrate and the light absorbing layer. When the light shielding film of the application is used in an optical element, the light absorbing layer can not be in direct contact with the substrate, and the light absorbing layer can be relatively thick to ensure the stability and light shielding effect of the light shielding layer. The matching layer can be made of a high refractive index material, and after being combined with the transparent substrate, it can reduce the reflected light between the light shielding film and the transparent substrate, thereby reducing the problem of stray light and ghosting. The matching layer can mainly solve the problem of matching the refractive index of the transparent substrate, and can reduce the requirement for light absorption. The material thereof is not limited by the existing light absorbing layer material, and a high refractive index layer is mainly obtained. The light absorbing layer mainly plays a role in light absorption, and the requirement for the refractive index thereof can be reduced. Therefore, a material with high light absorption and low refractive index can be used to prepare the light absorbing layer. Compared with the traditional single-layer light shielding film, the preparation requirement of the light absorbing layer is reduced, and the material selection range of the light absorbing layer is widened. When combined with the high refractive index transparent substrate, the light absorbing layer can also be prepared by using traditional black ink.

[0033] FIG. 1 is a structural schematic diagram of an optical element according to an embodiment of the application. The optical element includes a transparent substrate 20 and a light shielding film 10. The transparent substrate 20 can be a glass substrate. The transparent substrate 20 can be a high refractive index glass substrate. In an embodiment, the refractive index of the glass substrate is greater than 1.7, such as 1.8, or higher, such as 1.84, etc.

[0034] FIG. 2 is a structural schematic diagram of a light shielding film 10 according to an embodiment of the application. Referring to FIGS. 1 and 2 together, the light shielding film 10 according to an embodiment of the application includes a light absorbing layer 12 and a matching layer 11. The matching layer 11 and the light absorbing layer 12 are arranged in layers. In the optical element, the matching layer 11 is combined with the transparent substrate 20 and is located between the transparent substrate 20 and the light absorbing layer 12.

[0035] The light absorbing layer and the matching layer will be introduced respectively below.

[0036] Light absorbing layer

[0037] Referring to FIG. 2, the light absorbing layer 12 can be a black light absorbing layer 12, and the refractive index thereof is between 1.5 and 1.7. Compared with the matching layer 11, the light absorbing layer 12 mainly provides light absorption and anti-reflection performance. Therefore, in order to obtain a light absorbing layer 12 with higher light absorption effect, the light absorbing coefficient of the light absorbing layer 12 in the 400 nm to 700 nm wave band according to an embodiment of the application can be 0.3 to 0.7 μm -1 . For example, the light absorbing coefficient of the light absorbing layer 12 can be 0.3 μm -1 , 0.35 μm -1 , 0.4 μm -1 , 0.45 μm -1 , 0.5 μm -10.55 μm -1 0.6 μm -1 0.65 μm -1 0.7 μm -1 or a value between any two of the above values.

[0038] In the light shielding film according to the embodiments of the present application, the light absorbing layer 12 can have a relatively low refractive index, and can have a relatively large thickness to achieve a better light absorbing effect and reduce the transmittance of the light shielding film 10. In one embodiment, the thickness of the light absorbing layer 12 can be 10-100 μm, such as 10-80 μm, such as 10-50 μm, such as 10-40 μm. For example, the thickness of the light absorbing layer 12 can be 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or a value between any two of the above values.

[0039] The light absorbing layer 12 can be formed by using conventional ink or by using numerical material. When formed by using ink, commercially available products having a refractive index of 1.6-1.64 can be used. When the light absorbing layer 12 is formed by using resin material, the material used to form the light absorbing layer 12 includes resin, inorganic filler, pigment, solvent and adhesive. The inorganic filler can be added in a relatively small amount to avoid affecting the film forming property of the light absorbing layer 12.

[0040] The resin can be thermosetting resin or UV curing resin. The thermosetting resin can be, for example, epoxy resin, polyimide, silicone resin, fluorine resin, etc. The UV curing resin can be, for example, acrylic resin, epoxy resin, polyimide, silicone resin, fluorine resin, etc.

[0041] The inorganic filler is high refractive index inorganic nano material. For example, the inorganic filler can be titanium dioxide, zirconium oxide and nano diamond. Since the refractive index of the light absorbing layer is relatively low, the inorganic filler can be added in a relatively small amount.

[0042] The pigment can be selected from black substances such as carbon black, titanium black and iron oxide.

[0043] The solvent can be an organic solvent such as propylene glycol methyl ether acetate (2-acetoxy-1-methoxypropane, PGMEA), tetrahydrofuran (THF), methyl ethyl ketone (MEK), ethyl acetate (EAC), ethylene glycol monobutyl ether acetate (BAC), N-methylpyrrolidone (NMP), acetone, toluene, alcohol, etc.

[0044] The adhesive can be, for example, a silane coupling agent. The adhesive can be mixed with the above components, or the adhesive can be coated on the surface of the substrate or the matching layer before the light-absorbing layer is coated to improve adhesion to the substrate.

[0045] In one embodiment, a siloxane material or a gel material can be added to the components of the resin material forming the light-absorbing layer. The siloxane material can be, for example, a silsesquioxane, and the sol-gel material can be, for example, an organic alkoxide or a metal alkoxide, etc. In addition, the light-absorbing layer can be formed solely from a silsesquioxane or a sol-gel material.

[0046] Matching layer

[0047] With continued reference to FIG. 2, the matching layer 11 can be a black light-absorbing layer 12 or a gray matching layer 11. The matching layer 11 has a refractive index greater than that of the light-absorbing layer 12, and its main function is to provide the high refractive index requirement for the light-shielding film 10. Therefore, the refractive index of the matching layer 11 is higher than that of the light-absorbing layer 12. In one embodiment, the refractive index of the matching layer 11 is Nm>1.7, and Nmmay be, for example, 1.75, 1.78, 1.8, 1.84, or higher. At the same time, since the matching layer 11 has relatively low requirements for light reflection and light absorption, the light absorption coefficient of the matching layer 11 can be lower than that of the light-absorbing layer 12. In one embodiment, the light absorption coefficient of the matching layer 11 in the 400 nm to 700 nm wavelength range is 0.3 to 0.5 μm -1 . For example, the light absorption coefficient of the matching layer 11 can be, for example, 0.3 μm -1 , 0.32 μm -1 , 0.34 μm -1 , 0.36 μm -1 , 0.38 μm -1 , 0.4 μm -1 , 0.42 μm -1 , 0.44 μm -1 , 0.46 μm -1 , 0.48 μm -1 , 0.5 μm -1Or the value between any two of the above values.

[0048] Because the matching layer 11 has a high refractive index, its thickness can be set relatively small. In one embodiment, the film thickness of the matching layer 11 can be 5–20 μm, for example 5–15 μm, or even 5–10 μm. Exemplarily, the thickness of the matching layer 11 can be, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or any two of these values.

[0049] In this embodiment, the extinction coefficient of the matching layer at wavelengths from 400 nm to 700 nm is 0.001 μm. -1 To less than 0.03μm -1 For example, the extinction coefficient can be 0.0017–0.025 μm. -1 For example, the extinction coefficient of the matching layer may be 0.001 μm. -1 0.002μm -1 0.005μm -1 0.008μm -1 0.01μm -1 0.012μm -1 0.015μm -1 0.018μm -1 0.020μm -1 0.022μm -1 0.025μm -1 0.028μm -1 or 0.029μm -1 Or any value between the two values ​​above. Using a matching layer with the above extinction coefficient can reduce the manufacturing difficulty of the matching layer, broaden the range of diffusion materials, and help reduce the reflectivity between the light-shielding film and the substrate, thus reducing stray light.

[0050] The material forming the matching layer 11 can be a resin material or an inorganic gel material. When the material forming the matching layer 11 is a resin material, the material forming the matching layer 11 can include resin, inorganic filler, pigment, solvent and adhesive.

[0051] The resin can be a thermosetting resin or a UV-curable resin. Examples of thermosetting resins include epoxy resin, polyimide, silicone resin, and fluorite resin. Examples of UV-curable resins include acrylic resin, epoxy resin, polyimide, silicone resin, and fluorite resin.

[0052] The inorganic filler is an inorganic nano-material with high refractive index. Exemplarily, the inorganic filler can be, for example, titanium dioxide, zirconium oxide and nano-diamond. Since the matching layer needs to have the property of high refractive index, the content of the inorganic filler in the numerical material forming the matching layer is relatively high, so as to obtain a matching layer with high refractive index. When the content of the inorganic filler is increased in order to obtain a matching layer with high refractive index, the thickness of the matching layer needs to be set relatively low to prevent the decline of the stability of the matching layer caused by too much inorganic filler.

[0053] The pigment can be selected from, for example, black substances such as carbon black, titanium black and iron oxide.

[0054] The solvent can be an organic solvent such as PGMEA, THF, MEK, EAC, BAC, NMP, acetone, toluene, alcohol and the like.

[0055] The adhesive can be, for example, a silane coupling agent. The adhesive can be mixed with the above components, or the adhesive can be coated on the surface of the substrate or the matching layer before coating the light-absorbing layer to improve the adhesion to the substrate.

[0056] In an embodiment, a siloxane material or a gel material can be added to the components of the resin material forming the light-absorbing layer. The siloxane material can be, for example, a silsesquioxane, and the sol-gel material can be, for example, an organic alkoxide or a metal alkoxide. In addition, the light-absorbing layer can be formed solely by the silsesquioxane or the sol-gel material.

[0057] In an embodiment, the resin material forming the matching layer can include, for example, by weight fraction, resin, inorganic filler, pigment, solvent and adhesive. In the matching layer material of this embodiment, the inorganic filler is added in a relatively high amount, and therefore, when the matching layer is prepared using this material, the thickness of the matching layer can be relatively low. In an embodiment, the volume fraction of the resin is 10-98%, the volume fraction of the inorganic filler is 0.1-60%, and the volume fraction of the pigment is 0.01-30%. Exemplarily, the volume fraction of the resin can be, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 98% or any value between any two of the above values. The volume fraction of the inorganic filler can be, for example, 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or any value between any two of the above values. The volume fraction of the pigment can be, for example, 0.01%, 0.1%, 1%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 24%, 27%, 30% or any value between any two of the above values.

[0058] The light shielding film provided by the embodiments of the present application is a double-layer film structure. Compared with a single-layer light shielding film, the light shielding film has a high refractive index, a low reflectivity and high reliability. In an embodiment, the refractive index of the light shielding film is greater than 1.8. In addition, the light shielding film of the embodiments of the present application can be applied to a transparent substrate surface with a high refractive index. The light shielding film reduces stray light at the interface between the matching layer and the transparent substrate by utilizing the interaction between the matching layer and the transparent substrate.

[0059] Referring to FIG. 1, the optical element of the embodiments of the present application has a transparent substrate 20 on the light-in side and a light-absorbing layer 12 on the light-out side. Light is transmitted from the transparent substrate 20 to the matching layer 11 and is refracted by the matching layer 11 to enter the light-absorbing layer 12. In order to reduce the reflected light at the interface between the transparent substrate 20 and the matching layer 11, the refractive index Nm of the matching layer 11 in the optical element of the present application is in the range of 0.85Ns to 1.03Ns, such as 0.89Ns to 1.03Ns, such as 0.92Ns to 1.03Ns, such as 0.95Ns to 1.02Ns, such as 0.985Ns to 1.02Ns. In the embodiments of the present application, the refractive index of the transparent substrate 20 is greater than 1.7, such as greater than 1.8, such as greater than 2.0. The light shielding film of the present application can be used in a high-refractive-index substrate to reduce the stray light and imaging problems of a high-refractive-index optical element and reduce the manufacturing difficulty of the high-refractive-index optical element, so that it is possible to process and prepare a high-refractive-index and low-reflectivity optical element.

[0060] Figure 3 is a schematic diagram of the transmission path of light in an optical element according to an embodiment of the present application. As shown in Figure 3, after the external light is transmitted to the interface between the transparent substrate 20 and the matching layer 11, most of the light enters the matching layer 11, and a small amount of light is reflected back into the transparent substrate 20. The light transmitted through the matching layer 11 to the interface between the light-absorbing layer 12 and the matching layer 11 mostly enters the light-absorbing layer 12 and is absorbed by the light-absorbing layer 12, and a small amount of light is reflected back into the matching layer 11. After passing through the light-absorbing layer 12, most of the light is reflected back to the light-absorbing layer 12 at the back of the light-absorbing layer 12 and is repeatedly absorbed. Since the light-absorption coefficients of the matching layer 11 and the light-absorbing layer 12 are both high, most of the light entering the matching layer 11 and the light-absorbing layer 12 is absorbed. The reflected light mainly depends on the reflection at the interface between the transparent substrate 20 and the matching layer 11, and thus the reflectivity of the optical element mainly depends on the reflection at the interface between the transparent substrate 20 and the matching layer 11. Since the difference between the refractive indices of the matching layer 11 and the transparent substrate 20 is small, the reflectivity at the interface between the two is also low. Through the combined action of the matching layer 11 and the light-absorbing layer 12, the reflectivity of the optical element according to the embodiment of the present application can be less than 1%, or even less than 0.5%, or even less than 0.01%. The refractive index of the matching layer 11 is close to or the same as that of the substrate, so as to weaken the problem of stray light and ghosting between the light-blocking film 10 and the substrate to the greatest extent.

[0061] The structure of the optical element is explained above, and the performance of the optical element according to the present application is further verified and explained below in combination with test data.

[0062] Embodiment 1

[0063] This embodiment is an optical element including a glass substrate, a matching layer and a light-absorbing layer. The refractive index of the glass substrate is 1.84, the refractive index of the matching layer is 1.84, and the refractive index of the light-absorbing layer is 1.53. The light-absorbing layer is a black ink layer. The matching layer can be a black matching layer or a gray matching layer.

[0064] Embodiments 2-9

[0065] Embodiments 2-9 are optical elements respectively, and the structures thereof are the same as that of Embodiment 1, except that the parameters of the layers are different, and the specific parameters are listed in Table 1.

[0066] Comparative Example 1

[0067] The structure of the optical element of the comparative example is the same as that of Embodiment 1. The difference is that the value of Nm in the comparative example is not within the range defined in the present application.

[0068] Comparative Example 2

[0069] The optical element of the comparative example includes a glass substrate and an absorbing layer, and does not include a matching layer. The refractive index of the glass substrate is 1.84, and the absorbing layer is an ink layer, and the refractive index is 1.63.

[0070] The reflectivity of the optical elements of different embodiments and comparative examples was tested respectively, and the test results are shown in Table 1.

[0071] Table 1

[0072] Note: When testing the reflectivity of the optical elements of different embodiments and comparative examples, the incident angle of the test light beam is 68°.

[0073] As can be seen from the test data of Examples 1 to 9 in Table 1, the reflectivity of the optical elements of the embodiments is all below 1%. The reflectivity of some embodiments is all below 0.1%. As can be seen, the optical elements of the embodiments can obtain optical elements with lower reflectivity when high refractive index glass is used.

[0074] As can be seen from the test data of Examples 1 to 3, when the refractive index of the substrate is 1.84, the refractive index of the matching layer can be close to the refractive index of the substrate, and the refractive index of the absorbing layer can be set to be relatively low, and the absorbing layer with a refractive index of 1.53 can be obtained by using traditional commercially available ink. The final reflectivity of the optical elements corresponding to Examples 1 to 3 is all below 0.1%. When the refractive index of the matching layer changes, the reflectivity of the corresponding optical element changes slightly, but the change is not large.

[0075] As can be seen from the comparative data of Examples 1 and 4, when the refractive index of the absorbing layer is increased, the reflectivity of the optical element has a downward trend.

[0076] As can be seen from the comparative data of Examples 4 and 5, when the thickness of the matching layer is increased, the reflectivity of the optical element can be further reduced.

[0077] As can be seen from the test data of Examples 6 and 7, by changing the light absorption coefficient of the matching layer and the thickness of the matching layer, the reflectivity of the final optical element can be changed.

[0078] As can be seen from the test data of Example 8, the greater the difference between the refractive index of the matching layer and the refractive index of the substrate, the greater the reflectivity of the obtained optical element, which indicates that the difference between the refractive index of the matching layer and the refractive index of the substrate has an important influence on the reflectivity of the final optical element.

[0079] As can be seen from the test data of Example 9, when the refractive index of the substrate is 1.84 and the refractive index of the matching layer is 1.81, the final reflectivity of the optical element can be greatly improved. However, even if the combination of Example 9 is used, an optical element with a reflectivity of less than 1% can be obtained.

[0080] As can be seen from the comparison data of Example 4 and Comparative Example 1, when the refractive index difference between the matching layer and the substrate is large, such as the refractive index of the matching layer in Comparative Example 1 is 1.51, the reflectivity of the corresponding optical element reaches 62.4%.

[0081] As can be seen from the test of Comparative Example 2, when the optical element does not contain a matching layer, the reflectivity of the corresponding optical element is 49%.

[0082] As can be seen from the above comparison, the light shielding film of the embodiments of the present application can obtain better light shielding effect, especially in the application scenario of high refractive index glass, which can greatly reduce the reflectivity of the optical element.

[0083] FIG. 4 is a reflectivity test diagram of an optical element with different thicknesses of the matching layer. In FIG. 4, (a) is a reflectivity spectrum under different light absorption coefficients, and (b) is an enlarged view of A in (a). As shown in FIG. 4, as the thickness of the matching layer increases, the overall reflectivity of the optical element shows a downward trend. In addition, when the light absorption coefficient of the matching layer is 0.3-0.5 μm -1 , the reflectivity of the optical element is all below 0.01%.

[0084] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A light shielding film for being provided on a surface of a transparent substrate, characterized by, The light shielding film comprises a matching layer and a light absorbing layer, the matching layer and the light absorbing layer are stacked, the matching layer is used to connect with the transparent substrate, the refractive index Nm of the matching layer is greater than the refractive index Na of the light absorbing layer, and the refractive index Nm of the matching layer ranges from 0.85Ns to 1.03Ns, and Ns is the refractive index of the transparent substrate.

2. The light shielding film according to claim 1, wherein The refractive index Nm of the matching layer ranges from 0.985Ns to 1.02Ns.

3. The light shielding film according to claim 1 or 2, wherein The extinction coefficient of the matching layer in the 400-700 nm band is greater than or equal to 0.0017 and less than 0.03 μm -1 .

4. The light shielding film according to any one of claims 1 to 3, wherein The extinction coefficient of the matching layer in the 400nm-700nm waveband is 0.0017-0.025μm -1 .

5. The light shielding film according to any one of claims 1 to 4, wherein The refractive index of the light shielding film is greater than 1.

8.

6. The solar control film of any of claims 1-5, wherein, The light absorption coefficient of the matching layer in the 400-700 nm band is 0.3-0.5 μm -1 .

7. The solar control film of any of claims 1-6, wherein, The film thickness of the matching layer is 5-20μm.

8. The solar control film of any of claims 1-7, wherein, The light absorption coefficient of the light absorption layer in the 400-700 nm waveband is 0.3-0.7 μm -1 .

9. The solar control film of any of claims 1-8, wherein, The film thickness of the light absorbing layer is 10-100μm.

10. The solar control film of any of claims 1-9, wherein, The refractive index of the light absorbing layer is 1.5-1.

7.

11. The solar control film of any of claims 1-10, wherein, The material of the matching layer comprises resin, inorganic filler and pigment, in the matching layer, the volume percentage of the resin is 10-98%, the volume percentage of the inorganic filler is 0.1-60%, and the volume percentage of the pigment is 0.01-30%.

12. An optical element, characterized by, The transparent substrate and the light shielding film on the surface of the transparent substrate, the matching layer is arranged between the transparent substrate and the light absorbing layer and connected with the transparent substrate, the light entering side of the optical element is the transparent substrate side, the refractive index Ns of the transparent substrate is greater than 1.7, and the reflectivity of the optical element is less than 1%.

13. An electronic device, comprising: The optical element comprises the optical element of claim 12.

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