Light diffusion type anti-reflection film

Abstract

The invention discloses a light diffusion type anti-reflection film. The light diffusion type anti-reflection film comprises a transparent substrate and a multi-layer scattering structure, the transparent substrate is provided with a first surface and a second surface which are opposite. The multi-layer scattering structure is arranged on the first surface. The multi-layer scattering structure comprises a first scattering layer, a second scattering layer and a third scattering layer. The second scattering layer is stacked above the first scattering layer, and the third scattering layer is stacked above the second scattering layer. The second scattering layer is provided with a first interface facing the first scattering layer and a second interface facing the third scattering layer, and the first interface and the second interface are in an asymmetrical and non-uniformly distributed wavy profile. Therefore, the invention achieves excellent and stable diffusion and anti-reflection effects.

Description

Technical Field

[0001] The present invention relates to an optical film, in particular to a light diffusion type anti-reflection film. Background Art

[0002] Current display technology is moving toward higher pixel densities, placing higher performance demands on the optical film structures used with display panels, such as anti-glare film (AG film) and anti-reflection film (AR film). Traditional anti-glare films are often roughened by sandblasting or die-casting on the surface of transparent substrates, using haze to control the scattering behavior of light (haze refers to the percentage of scattered light flux that deviates from the direction of incident light when light passes through a transparent or translucent material, compared to the total transmitted light flux). However, if the haze is too low, glare may occur; conversely, if the haze is too high, image contrast may decrease and the dynamic scattering effect may be uneven, affecting picture quality. Another type of anti-glare film is a coating containing inorganic particles applied to the surface of a transparent substrate. The microstructure formed by the particles produces a scattering effect, but this method is often accompanied by problems such as uneven brightness distribution and severe light loss.

[0003] On the other hand, traditional anti-reflection films are usually formed into a multi-layer interference structure through processes such as sputtering or wet coating. Although these films have excellent anti-reflection properties, such processes are costly, complex, and have poor adhesion between the film layer and the substrate, making them unsuitable for long-term use and mass production.

[0004] In other words, the optical film structures in the prior art, whether anti-glare films or anti-reflection films, have room for improvement in terms of optical performance and cost control. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a light-diffusion anti-reflection film to address the deficiencies of the prior art.

[0006] To address the aforementioned technical issues, one of the technical solutions employed by the present invention is to provide a light-diffusing anti-reflection film comprising a transparent substrate and a multilayer scattering structure. The transparent substrate has a first surface and a second surface facing each other. The multilayer scattering structure is disposed on the first surface. The multilayer scattering structure includes a first scattering layer, a second scattering layer, and a third scattering layer. The second scattering layer is stacked above the first scattering layer, and the third scattering layer is stacked above the second scattering layer. The second scattering layer has a first interface facing the first scattering layer and a second interface facing the third scattering layer. The first and second interfaces exhibit asymmetric and non-uniformly distributed wavy profiles.

[0007] One of the beneficial effects of the present invention is that the light-diffusing anti-reflection film F provided herein employs a multilayer scattering structure of at least three layers, wherein adjacent scattering layers within the multilayer scattering structure have different refractive indices. Consequently, the present invention utilizes the technical feature of the multilayer scattering structure in which "the second scattering layer 2 has a first interface facing the first scattering layer and a second interface facing the third scattering layer, and the first and second interfaces exhibit asymmetric and non-uniformly distributed wavy profiles" to uniformly diffuse light passing through the light-diffusing anti-reflection film without reducing brightness.

[0008] Compared to traditional diffuser films that require precise alignment and lamination to avoid interference fringes or Moiré patterns, the multi-layer scattering structure used in this invention features an asymmetric and disordered wavy profile, allowing light to diffuse through the multi-layer scattering layer at multiple angles and directions. This not only reduces ambient light crosstalk and optical loss, but more importantly, achieves excellent and stable diffusion and anti-reflection effects without the need for strict alignment and lamination during the manufacturing process.

[0009] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and illustration and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. 1 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a first embodiment of the present invention.

[0011] Figure 2 Schematic diagram of the processing direction of the light-diffusing anti-reflection film of the present invention during the production process.

[0012] Figure 3 FIG. 1 is a cross-sectional schematic diagram of another state of the light-diffusing anti-reflection film according to the first embodiment of the present invention.

[0013] Figure 4 FIG. 1 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a second embodiment of the present invention.

[0014] Figure 5 FIG. 4 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a third embodiment of the present invention.

[0015] Figure 6 FIG. 4 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a fourth embodiment of the present invention.

[0016] Figure 7 FIG. 4 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a fifth embodiment of the present invention.

[0017] Figure 8 FIG. 4 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a sixth embodiment of the present invention.

[0018] Figure 9 FIG. 1 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a seventh embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following is an explanation of the embodiments of the "light-diffusion anti-reflective film" disclosed in the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual size. Please note that the following embodiments will further explain the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of protection of the present invention.

[0020] It should be understood that although terms such as "first," "second," and "third" may be used herein to describe various components, these components should not be limited by these terms. These terms are primarily used to distinguish one component from another. In addition, the term "or" as used herein may include any one or more combinations of the associated listed items, depending on the actual situation.

[0021] First embodiment

[0022] See Figure 1 As shown, Figure 1 The figure is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a first embodiment of the present invention. The present invention provides a light-diffusing anti-reflection film F, which primarily comprises: a multilayer scattering structure and a transparent substrate 6. The transparent substrate 6 has a first surface 61 and a second surface 62 facing each other. The multilayer scattering structure is disposed on the first surface 61, and the multilayer scattering structure has at least three scattering layers, preferably three to five layers. Each scattering layer is made of a light-transmitting material. For example, each scattering layer can be made of a material commonly found in anti-glare film (AG film) or anti-reflection film (AR film), such as polymethyl methacrylate (PMMA), polycarbonate (PC), or a styrene-based polymer, mixed with scattering inorganic particles such as titanium oxide (TiO2), silicon oxide (SiO2), or barium sulfate (BaSO4). The material of the transparent substrate 6 is polyethylene terephthalate (PET) or polycarbonate (PC). The present invention is not limited by the materials of the scattering layer and the transparent substrate 6.

[0023] In the present invention, adjacent scattering layers have different refractive indices. Specifically, the difference in refractive index between the two adjacent scattering layers is greater than or equal to 0.1. By configuring the multi-layer scattering structure with different refractive index materials, a graded refractive index structure is formed along the thickness direction, causing light to undergo multiple refractions and scattering during its transmission. This produces a significant multiple scattering effect, effectively improving light diffusion performance while also helping to suppress reflections and spotting, further enhancing anti-reflection performance and visual uniformity.

[0024] For example, if Figure 1 As shown, in the first embodiment, the multilayer scattering structure is a three-layer structure comprising a first scattering layer 1, a second scattering layer 2, and a third scattering layer 3. The first scattering layer 1 is disposed on the first surface 61 of the transparent substrate 6, the second scattering layer 2 is stacked above the first scattering layer 1, and the third scattering layer 3 is stacked above the second scattering layer 2. The second scattering layer 2 has a first interface B1 facing the first scattering layer 1 and a second interface B2 facing the third scattering layer 3. The first interface B1 and the second interface B2 exhibit asymmetric and non-uniformly distributed wavy profiles. More specifically, the first interface B1 of the second scattering layer 2 is in contact with the first scattering layer 1, and the second interface B2 of the second scattering layer 2 is in contact with the third scattering layer 3. The refractive index difference between the first scattering layer 1 and the second scattering layer 2, and the refractive index difference between the second scattering layer 2 and the third scattering layer 3, is greater than or equal to 0.1.

[0025] The first interface B1 and the second interface B2 exhibit asymmetric and non-uniform wavy profiles. In the present invention, the average amplitude of the first interface B1 or the second interface B2 of the second scattering layer 2 ranges from 0.1 μm to 10 μm. It should be noted that the average amplitude referred to here is defined as the average amplitude obtained by selecting several pairs of corresponding local maxima and adjacent local minima along the cross-sectional profile of the first interface B1 or the second interface B2, calculating the height differences between each pair, and taking the average of these multiple height differences as the average amplitude. For example, five pairs of corresponding local maxima and adjacent local minima along the cross-sectional profile of the first interface B1, for example, five local maxima and five local minima, are selected, and the height differences between each pair are calculated. The average of these multiple height differences is taken as the average amplitude. Furthermore, the thickness of the second scattering layer 2, that is, the distance between the first interface B1 and the second interface B2, can be divided into multiple wide thickness regions W1 and multiple narrow thickness regions W2. Multiple wide thickness regions W1 and multiple narrow thickness regions W2 are randomly distributed within the thickness range, and the wide thickness regions W1 and the narrow thickness regions W2 do not overlap with each other in a regular manner. The average thickness of the wide thickness regions W1 ranges from 5 μm to 20 μm, and the average thickness of the narrow thickness regions W2 ranges from 0.1 μm to 5 μm.

[0026] The upper surface of the first scattering layer 1 (i.e., in the first embodiment) Figure 1 The first interface B1) in the embodiment may be a rhombus surface, a pyramid surface, a wavy surface or an arc surface, and the present invention is not limited thereto. For example, the upper surface of the first scattering layer 1 may be an asymmetric and non-uniform wavy surface. Alternatively, Figure 3 In another state shown, the upper surface of the first scattering layer 1 is a prism surface. Figure 3 From a cross-sectional perspective, it is a serrated surface composed of multiple diamond-shaped structures.

[0027] See Figure 2 , Figure 2 Schematic diagram of the processing direction of the light-diffusion anti-reflection film of the present invention during the manufacturing process. During the manufacturing process, the rolled light-diffusion anti-reflection film F will be extended along a processing direction D and cut into multiple sections. The outer surface 31 of the third scattering layer 3 is a non-flat surface, presenting a curved texture structure extending along a predetermined direction, and the ten-point average roughness (Rz) of the outer surface 31 is between 0.1μm and 10μm), and the predetermined direction is the processing direction D of the light-diffusion anti-reflection film F in the process. Observing the third scattering layer 3 from a top view, the curved texture structure presents the morphology of irregular water lines (not shown in the figure); and observing the cross-section of the third scattering layer 3, the curved texture structure presents an asymmetric and non-uniform concave-convex morphology (see Figure 1 ).

[0028] It's worth noting that many of these curved textures are microstructures, with characteristic scales typically ranging from hundreds of nanometers to tens of micrometers. These structures can only be discerned through magnification, such as optical or electron microscopy. These microstructures help improve the film's light diffusion properties, while also suppressing reflective glare and enhancing display quality.

[0029] Furthermore, the multi-layer scattering structure adopted in the present invention can cause part of the light to be scattered weakly multiple times between the interfaces of different layers, thereby producing a higher-order small-angle scattering effect. This scattering phenomenon is called soft diffusion in optical film applications. Compared with the strong diffusion formed by traditional single-layer diffusion films, soft diffusion does not produce obvious boundary shadows (hard shadows), but can blur the edges of the object contours, produce a soft light effect, and improve visual comfort. This flexible diffusion phenomenon can evenly disperse strong light, effectively improve the viewer's discomfort, and improve color uniformity and picture contrast while avoiding obvious brightness attenuation. In addition, soft diffusion can flatten the brightness distribution of the light source, so that there is a natural transition between bright and dark areas, which helps to improve the overall picture level and quality. It is particularly suitable for application fields such as LCD, OLED displays, backlight modules and lighting equipment.

[0030] In the present invention, the haze range of the light-diffusing anti-reflective film is preferably 3% or more and less than 60%, more preferably 5% or more and less than 20%. The control of the haze value has a key impact on the performance of the optical film. Too low a haze may cause glare, while too high a haze may cause image blur and brightness loss. Although the common haze range of about 10% to 80% is easier to achieve, in order to take into account both the anti-glare effect and clarity, the present invention preferably adopts a design with a haze of less than 20% but greater than 5%, and achieves this range through the refractive index difference and microstructure control of the multi-layer scattering material.

[0031] For example, when the light-diffusing anti-reflective film of the present invention is applied to a backlight module, that is, when it is used as a diffusion film for the backlight module, light is incident from the second surface 62 where the transparent substrate 6 is located, and the light passes through the multi-layer scattering structure, and then generates multiple scattering at the interfaces of the layers with different refractive indices and the microstructure, making the light output softer and more uniform, thereby effectively eliminating the phenomenon of sparkle or spot concentration, and improving the overall brightness uniformity of the panel.

[0032] In another embodiment (such as Figure 8), light can also be incident on the first surface 61 of the transparent substrate 6. It first passes through the multi-layer scattering structure disposed above the first surface 61. The light is then scattered weakly by the difference in refractive index between the layers and the non-uniform wavy interfaces B1 and B2, forming a uniformly diffused light. Subsequently, the diffused light passes through the optical functional layer 7 (e.g., the brightness enhancement structure 71) disposed on the second surface 62 of the transparent substrate 6, further providing a composite optical effect of diffusion and brightness enhancement.

[0033] On the other hand, when the light-diffusion anti-reflection film of the present invention is used as an anti-glare anti-reflection film (for example, attached to the surface of a display such as microLED, mini LED, OLED, or LCD), the user views the screen from above, and the incident light first contacts the outermost layer of the multi-layer scattering structure (at the bottom). Figure 1 and Figure 3 In this embodiment, the outermost layer, the third scattering layer 3, has a roughened outer surface 31. The combined effects of its surface irregularities and refractive index differences scatter or suppress most light, significantly reducing ambient reflections and glare, thereby enhancing reading and viewing clarity. Light diffusion through these multiple layers of disordered microstructures prevents interference between the microstructures and high-resolution displays and reduces moiré patterns without increasing haze.

[0034] In another embodiment, the light-diffusing anti-reflection film of the present invention can also be applied to the display surface structure of televisions or large display devices. Through a multi-layer scattering layer structure and microstructured surface design, the present invention exhibits relatively high reflectivity in specific wavelength regions (e.g., red light wavelengths greater than 650nm) while simultaneously providing excellent light diffusion and anti-reflection properties in the visible light range. When applied to a display surface, it effectively atomizes light from the display light source, resulting in a soft and uniform light distribution effect on the screen, while reducing reflective crosstalk caused by ambient light, further improving the viewing quality and contrast clarity of the screen.

[0035] Furthermore, even though the light-diffusing anti-reflection film of the present invention possesses excellent scattering capabilities, it can still allow a laser pointer (such as a red laser pen) to be projected directly onto the surface of the film (e.g., the outer surface 31 of the third scattering layer 3) without causing the light spot to disappear due to absorption by the polarizing material. On the contrary, thanks to the moderate scattering properties, the laser light spot will produce a visual expansion effect on the film surface, making the originally tiny red dot appear larger and clearer, thereby improving the recognizability and practicality during presentations, displays, or interactive operations. In addition, if an appropriate amount of black particles is added to the scattering layer structure, background reflections can be further suppressed, enhancing the contrast effect. In particular, when the present invention adopts a five-layer scattering structure, the scattering and anti-reflection properties will be more significant, making it suitable for high-contrast and high-definition display applications.

[0036] It should also be noted that the materials comprising the multilayer scattering layers of the present invention (e.g., the first through fifth scattering layers) include high-refractive-index materials and low-refractive-index materials. The refractive index of the high-refractive-index materials ranges from approximately 1.56 to 1.70, while the refractive-index of the low-refractive-index materials ranges from approximately 1.40 to 1.55. While the refractive index difference between the layers of the present invention can enhance the scattering effect, there is no limit to the refractive index difference between the high-refractive-index and low-refractive-index materials and it can be adjusted based on actual design requirements. However, the refractive index difference must be at least 0.1.

[0037] Second embodiment

[0038] See Figure 4 As shown, Figure 4 FIG. 1 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a second embodiment of the present invention. Figure 4 The light diffusion anti-reflection film structure shown is the same as that of the first embodiment ( Figure 1 ) (i.e., the multi-layer scattering structure is based on a three-layer scattering layer as an example, with the first scattering layer 1 being the bottom layer and the third scattering layer 3 being the outermost layer), and the similarities are not repeated here. The main difference between the second embodiment and the first embodiment is that the outermost surface of the multi-layer scattering structure, i.e., the outer surface 31 of the third scattering layer 3, can be a flat surface, a prism surface, a pyramidal surface, a wavy surface, or an arc surface, and the present invention is not limited thereto. Figure 4 In the second embodiment, the outer surface 31 of the third scattering layer 3 can be a relatively flat surface with a ten-point average roughness (Rz) of less than 0.5 μm. Compared to the outer surface with a distinct curved texture in the first embodiment, the flat outer surface design in this embodiment helps further reduce interface reflectivity and improve the overall light transmittance of the light-diffusing anti-reflection film F.

[0039] Specifically, the flat outer surface can reduce the scattering and multiple reflections of light at the interface between the air and the film layer, thereby achieving an anti-reflection effect. At the same time, since the surface roughness of the outer surface 31 is extremely low, it is beneficial to improve the linear transmission efficiency of the light flux and achieve high light transmittance, which is suitable for use in display devices with high requirements for brightness and picture clarity. This design is also particularly suitable for automotive projection film applications (such as HUD head-up displays or windshield display systems). When the light emitted from the lower backlight source (such as the projection light in the automotive display module) penetrates the light-diffusion anti-reflection film provided by the present invention, it can be efficiently transmitted to the display interface through the low-roughness outer surface, further ensuring that the image has good clarity and sufficient brightness, thereby improving the overall user visual experience and driving safety.

[0040] Third embodiment

[0041] See Figure 5 As shown, Figure 5 FIG. 4 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a third embodiment of the present invention. Figure 5 The light diffusion anti-reflection film structure shown is the same as that of the first embodiment ( Figure 1 ) are similar, and the similarities are not repeated here. The main difference between the third embodiment and the first embodiment is that Figure 5 In the light-diffusing anti-reflection film F, the multilayer scattering structure includes, in addition to a first scattering layer 1, a second scattering layer 2, and a third scattering layer 3, a fourth scattering layer 4, and a fifth scattering layer 5. The first through fifth scattering layers are stacked sequentially from bottom to top, with the first scattering layer 1 disposed on the first surface 61 being the bottommost layer and the fifth scattering layer 5 being the outermost layer. The outermost surface of the multilayer scattering structure is the outer surface 51 of the fifth scattering layer 5. Figure 5 The outer surface 51 of the outermost layer is a flat surface, but the present invention is not limited thereto. In practice, it may also be a rhombus surface, a pyramid surface, a wavy surface or an arc surface, preferably a wavy surface.

[0042] The five-layer scattering layer design further enhances the multiple scattering effect of light within the film, allowing penetrating light to undergo more refraction and diffusion paths between the interfaces of each layer. This effectively improves the uniformity and directionality of light diffusion, achieving a softer and more delicate flexible diffusion effect. Compared to a three-layer structure, the five-layer design provides higher-order small-angle scattering, helping to eliminate localized bright spots, reduce the hardness of light source boundaries, and improve overall image consistency and visual comfort.

[0043] Fourth embodiment

[0044] See Figure 6 As shown, Figure 6 FIG. 4 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a fourth embodiment of the present invention. Figure 6 The light diffusion anti-reflection film structure shown is the same as that of the first embodiment ( Figure 1 ) are similar, and the similarities are not repeated here. The main difference between the third embodiment and the first embodiment is that the light diffusion anti-reflection film F further includes an optical function layer 7, which is disposed on the second surface 62 of the transparent substrate 6. The optical function layer 7 can be a flat surface, a rhombus surface, a pyramid surface, a wavy surface or an arc surface, and the present invention is not limited thereto. Figure 6 In the embodiment, the outer surface 71 of the optical functional layer 7 is a wavy surface with an asymmetric and unevenly distributed concave-convex structure. The ten-point average roughness (Rz) of the outer surface 71 can be controlled between 0.1 μm and 10 μm.

[0045] The design of the optically functional layer 7 effectively enhances the light scattering effect, further improving the light-diffusing capability of the overall structure of the light-diffusing anti-reflection film F. For example, in a display backlight module, light typically enters from below, passing through the optically functional layer 7 disposed on the second surface 62, and then enters the transparent substrate 6. It then travels upward to the various scattering layers (e.g., the first, second, and third scattering layers), ultimately exiting from the outer surface 31 of the third scattering layer 3 in the direction of the user's line of sight. In this application scenario, the optically functional layer 7 further diffuses light that penetrates the transparent substrate 6 from below, resulting in a more uniform and softer light output. This design also helps reduce high-angle reflections, thereby improving overall display quality and visual comfort.

[0046] However, the present invention does not limit the incident direction of light. In other embodiments, light can also be incident from above, that is, first passing through the multi-layer scattering structure (e.g., the third scattering layer 3, the second scattering layer 2, and the first scattering layer 1), then passing through the transparent substrate 6, and finally emitted by the optical functional layer 7 disposed on the second surface 62. Under this optical path configuration, the optical functional layer 7 can still control the outgoing light through its surface structure design (e.g., wavy surface, pyramidal surface, rhombus surface, or arc surface) to produce different optical effects, such as guiding light to increase brightness (brightness enhancement), diffusing the light field to achieve uniform light output (uniform light), or suppressing glare and reflective crosstalk. In other words, whether light penetrates the film from top to bottom or bottom to top, the present invention can effectively achieve the desired composite optical function through the structural configuration and profile characteristics of the optical functional layer, further enhancing the application flexibility and optical performance of the overall film.

[0047] Fifth embodiment

[0048] See Figure 7 As shown, Figure 7 FIG. 4 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a fifth embodiment of the present invention. Figure 7 The light diffusion anti-reflection film structure shown is the same as that of the first embodiment ( Figure 1 ) are similar, and the similarities are not repeated here. The main difference between the fifth embodiment and the first embodiment is that Figure 6 In the embodiment, the light-diffusing anti-reflection film F further includes an optical functional layer 7 disposed on the second surface 62 of the transparent substrate 6. The outer surface 71 of the optical functional layer 7 is an arc surface, presenting a concave-convex lens structure formed by regularly arranging multiple arc structures, with a smooth height variation characteristic.

[0049] For example, when used in a display backlight module, light from a lower backlight source first passes through the optically functional layer 7, then travels upward through the transparent substrate 6 to the various scattering layers, ultimately exiting from the outer surface 31 of the third scattering layer 3. The arc-shaped outer surface 71 of the optically functional layer 7 helps diffuse incident light from below, improving overall diffusion efficiency. Furthermore, compared to sharp or randomly rough structures, the arc-shaped concave and convex profile maintains uniform light output while diffusing the light, effectively reducing issues such as spotting, uneven brightness, and interference fringes, resulting in a more uniform light distribution effect.

[0050] On the other hand, in other embodiments, if light is incident from the direction of the multi-layer scattering structure, the light first passes through the multi-layer scattering structure with a gradient refractive index and interface microstructure, producing a uniform light diffusion effect. Subsequently, the optical functional layer 7 (e.g., a circularly arranged concave-convex lens structure) disposed on the second surface 62 of the transparent substrate 6 further controls the uniform light field, achieving functions such as light focusing, light guiding, or refraction in a specific direction. In other words, different optical properties can be achieved by utilizing different light input directions.

[0051] Sixth embodiment

[0052] See Figure 8 As shown, Figure 8 FIG. 4 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a sixth embodiment of the present invention. Figure 8 The light diffusion anti-reflection film structure shown is the same as that of the first embodiment ( Figure 1 ) are similar, and the similarities are not repeated here. The main difference between the sixth embodiment and the first embodiment is that Figure 8 In the embodiment, the light-diffusing anti-reflection film F further includes an optical functional layer 7 disposed on the second surface 62 of the transparent substrate 6. The outer surface 71 of the optical functional layer 7 exhibits a prism-like structure, which is formed by regularly arranged rhombus structures and has periodically arranged sharp corners and inclined surfaces.

[0053] This design is particularly suitable for LCD backlight modules (BLUs), optical light guides, solar energy collection systems, and various lighting devices. The composite structure used in this embodiment combines the two functions of light diffusion and light guiding. The multi-layer scattering structure performs preliminary diffusion and homogenization on the light from the light source, thereby compensating for the uneven brightness problem that may be generated by the prism-shaped optical functional layer 7 during the focusing process. This design can simultaneously achieve a comprehensive optical effect of improving brightness, maintaining light uniformity, and controlling light directionality. Furthermore, in the application of automotive optical systems, the optical functional layer 7 can not only effectively eliminate hot spots and improve glare, but also adjust the light direction through the arrangement angle of the prism (or sawtooth) structure, so that the light is concentrated and projected within the driver's line of sight, thereby greatly improving the brightness and clarity of the projected image, and achieving excellent display effects and driving safety.

[0054] Seventh embodiment

[0055] See Figure 9 As shown, Figure 9 FIG. 1 is a schematic cross-sectional view of a light-diffusing anti-reflection film according to a seventh embodiment of the present invention. Figure 9 The light diffusion anti-reflection film structure shown is the same as that of the first embodiment ( Figure 1 ) are similar, and the similarities are not repeated here. The main difference between the seventh embodiment and the first embodiment is that Figure 8 In the embodiment, the light-diffusing anti-reflective film F further includes an optically functional layer 7 disposed on the second surface 62 of the transparent substrate 6. The optically functional layer 7 is a privacy-preventing structure comprising a plurality of light-absorbing regions 701 and light-transmitting regions 702 arranged in an alternating pattern. The light-absorbing regions 701 are made of a black optical resin to absorb light in a specific direction; the light-transmitting regions 702 are made of a transparent or translucent optical resin to allow light of a normal viewing angle to pass through.

[0056] like Figure 9 As shown, light-absorbing regions 701 and light-transmitting regions 702 are alternately arranged on the second surface 62 of the transparent substrate 6, forming a directional privacy-preventing structure. When viewed from a normal viewing angle, light can penetrate the light-transmitting regions 702, presenting a clear image. However, when the viewing angle deviates from the normal direction (such as when viewing from the side), the line of sight falls on the light-absorbing regions 701, thereby obscuring the displayed content and achieving a privacy-preventing effect.

[0057] Furthermore, because the surface profile of the light-transmitting region 702 can be further adjusted (for example, by incorporating a microstructured texture design), it can also provide an effective light diffusion effect, making the emitted light softer and more uniform, further reducing glare and bright spots. Specifically, in this embodiment, light can be incident from the outer surface 31 of the third scattering layer 3, undergo multiple scattering and homogenization through the multi-layer scattering structure, and ultimately emitted from the optically functional layer 7 disposed on the second surface 62 of the transparent substrate 6. This configuration enables the multi-layer film to not only have an anti-reflective function, but also function as a highly efficient light diffusion film. Through this optical path design, the uniformity and light output angle range of the light can be significantly improved, thereby effectively expanding the viewing angle performance. Overall, the light-diffusing anti-reflective film F of the present invention combines the dual optical properties of diffusion and anti-peeping, making it particularly suitable for display applications that have dual requirements for privacy and visual quality, such as financial terminal equipment, in-vehicle information display systems, or mobile device screens.

[0058] In other embodiments, an additional light-transmitting film layer (not shown) may be disposed on the surface of the transparent substrate 6 to further enhance the optical properties of the film layer as a whole. The light-transmitting film layer may be a multi-layer film structure. For example, a multi-layer film structure composed of PET (polyethylene terephthalate) and PEN (polyethylene naphthalate) or other polymer materials with excellent optical transparency and mechanical stability may be used.

[0059] Furthermore, the optical behavior of the transparent film layer can be adjusted according to design requirements. For example, it can reflect light with a specific polarization direction (usually S light, i.e., light with a polarization direction perpendicular to the incident plane) back to the backlight module, while allowing light with a different polarization direction (usually P light, i.e., light with a polarization direction parallel to the incident plane) to pass through. Furthermore, the transparent film layer can also integrate diffusion and brightness enhancement functions to improve brightness performance and light output uniformity. In some applications, the transparent film layer can directly replace the transparent substrate 6. This design variation still maintains the optical functions of diffusion, anti-glare, anti-peeping, or brightness enhancement disclosed in the present invention, and can be modularly integrated according to application requirements, increasing process flexibility and design freedom.

[0060] Advantageous Effects of the Embodiments

[0061] Prior art light-diffusing film structures often utilize a single scattering layer. However, when used in high-resolution displays or backlight modules, these structures are still susceptible to visual crosstalk, such as bright spots or moiré patterns. In contrast, the light-diffusing anti-reflection film F provided by the present invention utilizes a multilayer scattering structure comprising at least three layers, wherein adjacent scattering layers within the multilayer scattering structure have different refractive indices. Consequently, the present invention utilizes the technical features of the multilayer scattering structure: "the second scattering layer 2 having a first interface B1 facing the first scattering layer 1 and a second interface B2 facing the third scattering layer 3, with the first interface B1 and the second interface B2 exhibiting asymmetric and non-uniformly distributed wavy profiles." This allows light passing through the light-diffusing anti-reflection film to be evenly diffused without compromising brightness.

[0062] For example, when the light-diffusing anti-reflection film F of the present invention is applied to a backlight module, light from below can smoothly penetrate the transparent substrate and diffuse evenly within the multi-layer structure, providing a soft and stable surface light source and effectively eliminating glare or bright spots. On the other hand, when applied to a display surface as an anti-glare anti-reflection film, when the user views from above, light is guided by the surface roughness and the difference in refractive index between the layers. Most of the ambient light is scattered or reflected, thereby reducing glare and improving display clarity.

[0063] The contents disclosed above are only preferred feasible embodiments of the present invention and do not limit the scope of protection of the claims of the present invention. Therefore, all equivalent technical changes made using the contents of the description and drawings of the present invention are included in the scope of protection of the claims of the present invention.

Claims

1. A light-diffusion anti-reflection film, characterized in that: The light-diffusion anti-reflection film comprises: a transparent substrate having a first surface and a second surface opposite to each other; and a multi-layer scattering structure disposed on the first surface, the multi-layer scattering structure comprising: a first scattering layer; a second scattering layer stacked on the first scattering layer; and a third scattering layer stacked on the second scattering layer; The second scattering layer has a first interface facing the first scattering layer and a second interface facing the third scattering layer. The first interface and the second interface present asymmetric and non-uniformly distributed wavy profiles.

2. The light-diffusion anti-reflection film according to claim 1, wherein The first interface of the second scattering layer is in contact with the first scattering layer, the second interface of the second scattering layer is in contact with the third scattering layer, and a refractive index difference between the first scattering layer and the second scattering layer, as well as a refractive index difference between the second scattering layer and the third scattering layer, is greater than or equal to 0.

1.

3. The light-diffusion anti-reflection film according to claim 1, wherein The upper surface of the first scattering layer is a rhombus surface, a pyramid surface, a wavy surface or an arc surface.

4. The light-diffusion anti-reflection film according to claim 1, wherein The average amplitude of the first interface or the second interface of the second scattering layer is between 0.1 μm and 10 μm, wherein the average amplitude is defined by selecting a plurality of pairs of corresponding local highest points and adjacent local lowest points on a cross-sectional contour line of the first interface or the second interface, calculating the height difference between each pair, and taking the average of the plurality of height differences as the average amplitude.

5. The light-diffusion anti-reflection film according to claim 1, wherein The thickness of the second scattering layer can be divided into a plurality of wide thickness regions and a plurality of narrow thickness regions, and the plurality of wide thickness regions and the plurality of narrow thickness regions are randomly distributed within the thickness range; wherein the average thickness of the wide thickness regions is between 5 μm and 20 μm, and the average thickness of the narrow thickness regions is between 0.1 μm and 5 μm; wherein the thickness of the second scattering layer is defined as the distance between the first interface and the second interface.

6. The light-diffusion anti-reflection film according to claim 5, wherein The plurality of wide thickness regions and the plurality of narrow thickness regions do not overlap with each other in an orderly manner.

7. The light-diffusing anti-reflection film according to claim 1, wherein When the third scattering layer is the outermost layer of the multi-layer scattering structure, the ten-point average roughness of the outer surface of the third scattering layer is between 0.1 μm and 10 μm.

8. The light-diffusion anti-reflection film according to claim 1, wherein When the third scattering layer is the topmost layer of the multi-layer scattering structure, the outer surface of the third scattering layer is a flat surface, a pyramid surface, a rhombus surface, a wavy surface or an arc surface.

9. The light-diffusing anti-reflection film according to claim 1, wherein The light-diffusion anti-reflection film further includes an optical functional layer disposed on the second surface of the transparent substrate.

10. The light-diffusion anti-reflection film according to claim 9, wherein The outer surface of the optical functional layer is a pyramid, a rhombus, a wavy surface or an arc surface.

11. The light-diffusing anti-reflection film according to claim 9, wherein The outer surface of the optical functional layer is an asymmetric and non-uniform wavy surface.

12. The light-diffusing anti-reflection film according to claim 9, wherein The optical functional layer includes a black optical resin.

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