A high polarization-maintaining optical film and a projection screen

Abstract

The present invention relates to a highly polarization-maintaining optical film, comprising: a base layer, the base layer having a lower surface of the base layer and an upper surface of the base layer opposite to the lower surface of the base layer, the lower surface of the base layer being a flat surface, the upper surface of the base layer being an uneven microstructured surface, and a reflective layer provided on the base layer, the reflective layer having a lower surface of the reflective layer and an upper surface of the reflective layer opposite to the lower surface of the reflective layer, the lower surface of the reflective layer being disposed on the upper surface of the base layer, the reflective layer being substantially conformal to the upper surface of the base layer, so that the upper surface of the reflective layer forms a microstructured surface substantially consistent with the upper surface of the base layer; wherein, the angle θ between the tangent plane at any point on the upper surface of the reflective layer and the plane parallel to the lower surface of the base layer is controlled to randomly vary between 0 degrees and + / −30 degrees. This highly polarization-maintaining optical film has excellent polarization direction retention, reflectivity, gain, and viewing angle performance; the present application also provides a projection screen prepared from the highly polarization-maintaining optical film, which has high definition and low cost, and is beneficial to the promotion of the 3D movie market.

Description

Technical Field

[0001] The present invention relates to an optical film, and particularly to a high polarization-maintaining optical film and a projection screen. Background Art

[0002] 3D movies use a stereoscopic vision display system. The reproduced images are stereoscopically displayed by projecting the left-eye and right-eye plane projection images, enabling the audience to have a stronger sense of three-dimensional depth in the images, making them feel as if they are on the scene and more exciting. The quality of the 3D effect largely depends on the quality of the screen. Usually, the parameters for evaluating the screen performance are mainly gain, viewing angle, and polarization contrast. The principle of 3D is that the polarized light emitted from the projector is reflected by the screen and then enters the human eye through polarized glasses. Therefore, the screen needs to have very high polarization-maintaining performance. The higher the polarization contrast index, the smaller the double image and the stronger the three-dimensional sense. When the polarization-maintaining performance of the screen is poor, the problem of "ghost images" often occurs.

[0003] The gain and viewing angle of the screen are also two important indicators affecting the viewing effect. Gain is the reflection ability of the screen to light, which is the key to determining the picture brightness and an important parameter for image brightness improvement. Gain is determined by the surface material of the screen. The viewing angle here does not refer to the visible angle but the optimal viewing angle, which is the angle at which people can clearly observe all the content on the screen from different directions. The viewing angle and gain are relative concepts. Gain is closely related to the viewing angle and complements each other. When the gain is large, the viewing angle will naturally decrease. How to balance the relationship between the two has become the focus of the industry.

[0004] Currently, the screens used for 3D movies can be classified by material as: white plastic screens, gray plastic screens, beaded screens, PVC screens, fiberglass screens, metal screens, and anti-light screens. Among them, metal screens are widely promoted in 3D cinemas. On the one hand, it is because the reflection of metal is higher, and the gain effect is good, which can improve the overall brightness of the movie, making it clearer and more beautiful. The viewing angle is also larger than that of the beaded screen and smaller than that of the white plastic screen. On the other hand, it is because of the polarization-maintaining performance of the metal. Conventional metal screens mainly spray a layer of metal on the surface of the substrate, and the surface shows continuous powdery particles. However, this process will cause great attenuation and waste of the light source of the projector, resulting in low picture brightness, obvious surface granularity, affecting the resolution of the picture, and unable to achieve true high definition. At the same time, since the metal powder is exposed to the air, it is extremely easy to oxidize and darken, greatly reducing the service life and bringing greater economic costs.

[0005] The method of controlling the reflection angle by designing the micro-structure on the surface of the substrate has begun to be applied to the screen market. After plating a metal layer and a protective layer, a metal screen is obtained. However, this structure often requires high-precision design and production, and the production cost is very high; if there are deviations in the design or production process, it will ultimately cause quality problems of the screen. Summary of the Invention

[0006] The embodiments of the present invention and their objectives are described and illustrated below by way of examples in combination with systems, tools, and methods. These examples are merely exemplary and illustrative, not restrictive. In different embodiments, one or more of the above market demands have been met by the present invention, while other embodiments are directed to other improvements.

[0007] The main objective of the present invention is to provide an optical film based on surface microstructure, which has excellent polarization-maintaining performance and can be used to produce a high-polarization-maintaining and high-definition picture quality screen. The screen has stronger three-dimensional sense, less ghosting, and does not have the problem of "ghost image".

[0008] Another objective of the present invention is to provide an optical film based on a flexible plastic film material as the base layer, which can be bent or folded, facilitating roll-to-roll production and transportation.

[0009] Another objective of the present invention is to provide an optical film based on metal as the reflective layer, which has low cost, long service life, and is easy to produce on a large scale.

[0010] Another objective of the present invention is to provide an exemplary manufacturing process for producing such an optical film based on metal as the reflective layer.

[0011] To achieve the above objectives, the present application provides a high-polarization-maintaining optical film, characterized in that the high-polarization-maintaining optical film includes: a base layer, the base layer having a lower surface of the base layer and an upper surface of the base layer opposite to the lower surface of the base layer, the upper surface of the base layer being an uneven microstructured surface, and a reflective layer provided on the base layer, the reflective layer having a lower surface of the reflective layer and an upper surface of the reflective layer opposite to the lower surface of the reflective layer, the lower surface of the reflective layer being disposed on the upper surface of the base layer, the reflective layer being substantially conformal to the upper surface of the base layer, so that the upper surface of the reflective layer forms a microstructured surface substantially consistent with the upper surface of the base layer; wherein, the angle θ between the tangent of any point on the upper surface of the reflective layer and the plane parallel to the lower surface of the base layer is controlled to randomly vary between 0 degrees and + / - 30 degrees.

[0012] As a further improvement of the present application, for any region with a dimension greater than 1 mm along the direction parallel to the lower surface of the base layer, the structure of the upper surface of the reflective layer is composed of at least two wave peaks and at least two wave valleys, and the wave peaks and wave valleys have a random structure.

[0013] As a further improvement of the present application, the probability of the angle θ between the tangent of any point on the upper surface of the reflective layer and the plane parallel to the lower surface of the base layer varies continuously with the angle θ.

[0014] As a further improvement of the present application, the angle θ has the highest probability of occurring at 0 degrees, and the probability of the angle θ occurring continuously decreases as the absolute value of the angle increases.

[0015] As a further improvement of the present application, the ratio of the maximum value to the minimum value of the probability of occurrence of the angle θ is less than 10:1.

[0016] As a further improvement of the present application, the ratio of the maximum value to the minimum value of the probability of occurrence of the angle θ is less than 2:1.

[0017] As a further improvement of the present application, the cross-section of the uneven microstructured surface is an arc structure or a wavy structure.

[0018] As a further improvement of the present application, the characteristic length L between adjacent wave peaks or adjacent wave valleys of the reflective layer is not greater than 0.5 mm.

[0019] As a further improvement of the present application, the characteristic length L between adjacent wave peaks or adjacent wave valleys of the reflective layer is not greater than 0.05 mm.

[0020] As a further improvement of the present application, the height difference between the wave peaks and wave valleys on the upper surface of the reflective layer is not greater than 100 μm.

[0021] As a further improvement of the present application, the height difference between the wave peaks and wave valleys on the upper surface of the reflective layer is not greater than 10 μm.

[0022] As a further improvement of the present application, the reflective layer is composed of multiple layers of media, and the coherent superposition of the reflected light through multiple interfaces of the multiple layers of media realizes high reflection of the incident light.

[0023] As a further improvement of the present application, the reflective layer is formed by alternately stacking two isotropic optical transparent materials with different refractive indices.

[0024] As a further improvement of the present application, the reflective layer has a reflectivity of more than 80% for light with a wavelength between 400 nm and 700 nm.

[0025] As a further improvement of the present application, the reflective layer is a metal layer.

[0026] As a further improvement of the present application, the thickness of the metal layer is 5 nm to 1 μm.

[0027] As a further improvement of the present application, the thickness of the metal layer is 20 nm to 50 nm.

[0028] As a further improvement of the present application, the metal layer is prepared from at least one of silver, aluminum, gold, metal oxides, metal halides, and metal nitrides.

[0029] As a further improvement of the present application, the metal layer is prepared by any one of magnetron sputtering and evaporation coating processes.

[0030] As a further improvement of the present application, an adhesion promoting layer is provided between the uneven microstructured surface and the metal layer.

[0031] As a further improvement of the present application, the adhesion promoting layer is made of silicon dioxide.

[0032] As a further improvement of the present application, the thickness of the silicon dioxide is 10 nm to 100 nm.

[0033] As a further improvement of the present application, the adhesion promoting layer is prepared by any one of magnetron sputtering and evaporation coating processes.

[0034] As a further improvement of the present application, an antioxidant layer is provided on the surface of the metal layer.

[0035] As a further improvement of the present application, the antioxidant layer is made of any one of silicon dioxide, titanium dioxide, and ITO.

[0036] As a further improvement of the present application, the antioxidant layer is prepared by any one of magnetron sputtering and evaporation coating processes.

[0037] As a further improvement of the present application, the highly polarization-maintaining optical film further includes a covering layer, the covering layer has a lower surface of the covering layer and an upper surface of the covering layer opposite to the lower surface of the covering layer, and the lower surface of the covering layer is disposed on the upper surface of the reflective layer.

[0038] As a further improvement of the present application, the uneven microstructured surface is prepared by any one of fast tool imprinting, surface cutting, surface etching, and sandblasting processes.

[0039] As a further improvement of the present application, the material of the base layer is a deformable flexible plastic film material.

[0040] As a further improvement of the present application, the flexible plastic film material is any one of PET, PVC, and PC.

[0041] To achieve the above object, a projection screen, characterized in that the projection screen includes: a frame, an optical film, and an elastic structure: the frame is made of a metal or plastic material; the optical film is composed of a plurality of the above-mentioned highly polarization-maintaining optical films and is spliced by glue; the elastic structure reasonably stretches the optical film and fixes it on the frame.

[0042] As a further improvement of the present application, the elastic structure is a spring.

[0043] As a further improvement of the present application, the optical film has holes formed by laser drilling.

[0044] The beneficial effects of the present invention are as follows: The present invention provides a specially designed high polarization-maintaining optical film. In the high polarization-maintaining optical film, the upper surface of the base layer is designed as an uneven microstructured surface, and a reflective layer that is substantially conformal to the upper surface of the base layer is designed on the upper surface of the base layer, so that the upper surface of the reflective layer forms a microstructured surface that is substantially the same as the upper surface of the base layer. This high polarization-maintaining optical film has excellent polarization direction retention, reflectivity, gain, and viewing angle performance; it can produce a high polarization-maintaining and high-definition picture quality screen, and at the same time can solve the problem of high cost of existing products, which is beneficial to the promotion of the 3D movie market. Description of the Drawings

[0045] Figure 1 It is a schematic structural diagram of an embodiment of a high polarization-maintaining optical film;

[0046] Figure 2 It is a schematic diagram of light reflection on a flat surface (A) and a rough surface (B);

[0047] Figure 3 It is a schematic diagram of incident light and reflected light on an arc;

[0048] Figure 4 It is a schematic diagram of the angles of reflected light at different depths of an arc on a microstructured surface;

[0049] Figure 5 It is a schematic diagram of the reflected light intensity distribution (A) and the topography probability distribution of the microstructure (B);

[0050] Figure 6 It is a schematic diagram of the reflected light intensity distribution (A) when σ = 40° and the depth-to-width ratio of the microstructure on the surface of the high polarization-maintaining optical film (B);

[0051] Figure 7 It is a schematic diagram of the reflected light intensity distribution (A) when σ = 20° and the depth-to-width ratio of the microstructure on the surface of the high polarization-maintaining optical film (B);

[0052] Figure 8 It is a schematic cross-sectional structural diagram of an embodiment of a high polarization-maintaining optical film;

[0053] Figure 9 It is a schematic diagram of the manufacturing process of an embodiment of a base layer with a microstructured surface;

[0054] In the figure: 01, base layer; 02, microstructured surface; 03, reflective layer; 04, covering layer; 05, holes; 06, embossing structure; 07, soft film structure; 001, incident light; 002, flat surface; 003, reflected light; 004, rough surface; 005, arc; 006, arc tangent; 007, included angle; 011, first arc; 012, second arc; 013, lower surface of the base layer; 014, upper surface of the base layer; 031, lower surface of the reflective layer; 032, upper surface of the reflective layer. Detailed implementation manners

[0055] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be clearly and completely described below in conjunction with specific embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments, and are not used to limit the scope of the present invention. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0056] To prepare a high polarization-preserving and high-definition picture quality screen, the present application provides a high polarization-preserving optical film. The high polarization-preserving optical film includes: a base layer 01, the base layer 01 having a lower surface 013 of the base layer and an upper surface 014 of the base layer opposite to the lower surface 013 of the base layer. The lower surface 013 of the base layer can be a flat surface or an uneven surface with microstructures or other structures. The upper surface 014 of the base layer is an uneven microstructured surface 02, and a reflective layer 03 provided on the base layer 01. The reflective layer 03 has a lower surface 031 of the reflective layer and an upper surface 032 of the reflective layer opposite to the lower surface 031 of the reflective layer. The lower surface 031 of the reflective layer is disposed on the upper surface 014 of the base layer. The reflective layer 03 is substantially conformal to the upper surface 014 of the base layer, so that the upper surface 032 of the reflective layer forms a microstructured surface substantially consistent with the upper surface 014 of the base layer. Among them, the included angle θ between the tangent plane of any point on the upper surface 032 of the reflective layer and the plane parallel to the lower surface 013 of the base layer is controlled to randomly vary between 0 degree and + / - 30 degrees.

[0057] As Figure 1 shown in, according to an embodiment of the present invention, the basic structure of the high polarization-preserving optical film disclosed herein includes three layers of materials: a base layer 01, a reflective layer 03, and a covering layer 04. The upper surface 014 of the base layer is an uneven microstructured surface 02. Both the base layer 01 and the reflective layer 03 are optical materials. The covering layer 04 is used to protect the surface of the high polarization-preserving optical film.

[0058] In the present application, the theoretical basis for the design of the uneven microstructured surface 02 of the upper surface 014 of the base layer is as follows: AsFigure 2 As shown, when a beam of incident light 001 hits a flat surface, its reflected light 003 will go out along the direction of specular reflection; when a beam of incident light 001 hits a rough surface, its reflection direction is related to the micro-structure of the surface. When this micro-structure exists in the form of an arc 005 or an approximate arc 005, as Figure 3 shown, taking the incident light 001 incident on the arc 005 as the radial line of the arc to make an arc tangent 006, it can be found that the reflection direction of the reflected light 003 has a close relationship with the tangent. By controlling the angle 007 between the tangent and the horizontal position, we can adjust the direction of the reflected light 003 line, thereby controlling the reflection angle. The angle θ between the upper surface 032 of the reflective layer and the horizontal plane parallel to the lower surface 013 of the base layer, that is, the surface inclination angle θ (the angle between the tangent and the x-axis):

[0059]

[0060] When the θ angle varies within the range from θ to θ + Δθ, the probability distribution of its angle is proportional to the length △x:

[0061]

[0062] The angle α of the reflected light is related to the angle θ. The reflection angle α refers to the angle between the reflected ray and the interface normal. Finally, we can obtain the distribution function of the reflected light angle:

[0063]

[0064] A scattering unit includes the range where x ranges from -1 to 1. In order to make the reflected light intensity near 0° of α have better aggregation, we need the value of dy / dx to be relatively large near 0°, while the value of d 2 y / dx 2 to be relatively small near 0°.

[0065] Considering that the incident light 001 does not enter from a single direction, there will be a probability distribution of the reflection angle after the incident light hits the micro-structured surface 02. This probability distribution is related to the size of the arc 005 on the micro-structured surface 02. Here we assume that the size of the circle forming the arc 005 is the same, so the factor affecting the reflection angle is the depth of the arc 005. As Figure 4 shown, when the arc 005 is relatively shallow, such as the first arc 011, the angle of the reflected light 003 is relatively small; when the depth of the arc 005 increases, such as the second arc 012, the angle of the reflected light 003 at a larger slope will increase accordingly. Therefore, the micro-structure of the micro-structured surface on the base layer shown here needs to follow a certain probability distribution. Through a known reflected light intensity distribution, we can deduce the topography distribution of the micro-structure of the micro-structured surface, as Figure 5 shown,

[0066] Reflected light intensity: G(α) = W(α)

[0067] Surface θ - angle distribution: P(θ) = W(2θ) = H(θ)

[0068] Here, we equally divide the surface width of the circular arc 005 into N parts, and the width of each part is 1 / N; meanwhile, we equally divide the θ - angle (0° to 45°) into M parts, and the angle of each part is 45° / M.

[0069] Number of distributions: K j = H(θ j )N

[0070] When the surface width varies within the range to , the tilt angle is θ j .

[0071] It can be seen from this that, as shown in Figure 6 and Figure 7 , when the σ - angle is equal to 40° and 20° respectively, the depth - to - width ratios of the circular arc 005 of the micro - structured surface 02 are 20:3 and 10:1 respectively. Here, the depth - to - width ratio is the ratio of the depth measurement value to the width measurement value, and the σ - angle is half of the α - angle. Therefore, through this method, we can fabricate the required micro - structured surface 02 according to the performance parameters required finally.

[0072] In this application, the commonly used parameters for evaluating the performance of the screen are: total reflectance, viewing angle, brightness gain, and polarization contrast. Among them, the total reflectance can be reflected in the viewing angle and brightness gain. Under the same total reflectance, the higher the brightness gain, the narrower the viewing angle; conversely, the larger the viewing angle. The higher the polarization contrast, the better the viewing effect. According to the above - mentioned theoretical basis, a high - polarization - maintaining optical film with an uneven micro - structured surface 02 can be prepared, with a total reflectance reaching more than 95%, a vertical - direction polarization contrast greater than 1000:1 or up to more than 2000:1. When the viewing angle of the screen is controlled in the + / - 60 - degree direction, the polarization contrast of the high - polarization - maintaining optical film can reach 200:1, effectively eliminating the problem of 3D movie ghosting; in addition, we can control the final viewing angle and gain by adjusting the micro - structured surface 02. The gain can be adjusted between 1.3 - 3.5, and the viewing angle can also be controlled between ±20° to ±50°. A large viewing - angle range can meet large - scale screening halls and attract more audiences.

[0073] In a preferred embodiment, for any region with a dimension greater than 1 mm along the direction parallel to the lower surface 013 of the base layer, the structure of the upper surface 032 of the reflective layer consists of at least two peaks and at least two valleys, and the peaks and valleys have a random structure with substantially no repeatability. In a preferred embodiment, the probability of the angle θ between the tangent plane at any point on the upper surface 032 of the reflective layer and the plane parallel to the lower surface 013 of the base layer varies continuously with the angle θ. In a preferred embodiment, the probability of the angle θ being 0 degrees is the highest, and the probability of the angle θ continuously decreases as the absolute value of the angle increases. In a further preferred embodiment, the ratio of the maximum value to the minimum value of the probability of the angle θ is less than 10:1. In a still further preferred embodiment, the ratio of the maximum value to the minimum value of the probability of the angle θ is less than 2:1.

[0074] In a preferred embodiment, the cross-section of the uneven microstructured surface 02 is an arc structure or a wave structure. As Figure 8 shown, in a preferred embodiment, the characteristic length L between adjacent peaks or adjacent valleys of the reflective layer 03 is not greater than 0.5 mm. In a further preferred embodiment, the characteristic length L between adjacent peaks or adjacent valleys of the reflective layer 03 is not greater than 0.05 mm. In a preferred embodiment, the height difference between the peaks and valleys on the upper surface 032 of the reflective layer is not greater than 100 μm. In a further preferred embodiment, the height difference between the peaks and valleys on the upper surface 032 of the reflective layer is not greater than 10 μm.

[0075] In a preferred embodiment, the reflective layer 03 is composed of multiple layers of media, and through the coherent superposition of the reflected light 003 at multiple interfaces, high reflection of the incident light 001 (reflectivity exceeding 80%) is achieved. In a preferred embodiment, the reflective layer 03 is formed by alternately stacking two isotropic optical transparent materials with different refractive indices. In a still further preferred embodiment, the reflective layer 03 has a reflectivity exceeding 80% for light with wavelengths between 400 nm and 700 nm.

[0076] In a preferred embodiment, the reflective layer 03 is a metal layer. In a further preferred embodiment, the metal layer is prepared from at least one of silver, aluminum, gold, metal oxides, metal halides, and metal nitrides, but the metal layer is not limited to being prepared from the above three metals or metal oxides, metal halides, and metal nitrides. In a preferred embodiment, the thickness of the metal layer is 5 nm to 1 μm. In a further preferred embodiment, the thickness of the metal layer is 20 nm to 50 nm. In a preferred embodiment, the process for preparing the metal layer includes but is not limited to magnetron sputtering, evaporation coating, etc.

[0077] In a preferred embodiment, an adhesion promoting layer is further provided between the uneven microstructured surface 02 and the metal layer. In a further preferred embodiment, the adhesion promoting layer is made of silicon dioxide. In a still further preferred embodiment, the thickness of the silicon dioxide is 10 nm to 100 nm. In a preferred embodiment, the process for preparing the adhesion promoting layer includes but is not limited to magnetron sputtering and evaporation coating.

[0078] In a preferred embodiment, an antioxidant layer is provided on the surface of the metal layer. In a further preferred embodiment, the antioxidant layer is made of any one of silicon dioxide, titanium dioxide, and ITO. In a preferred embodiment, the process for preparing the antioxidant layer includes but is not limited to magnetron sputtering and evaporation coating.

[0079] In a preferred embodiment, the highly polarization-maintaining optical film further includes a cover layer 04, the cover layer 04 having a lower surface of the cover layer 04 and an upper surface of the cover layer 04 opposite to the lower surface of the cover layer 04, and the lower surface of the cover layer 04 being disposed on the upper surface 032 of the reflective layer.

[0080] In a preferred embodiment, the uneven microstructured surface 02 is prepared by any one of fast tool imprinting, surface cutting, surface etching, and sandblasting processes. In a further preferred embodiment, the material of the base layer 01 is a deformable flexible plastic film material. In a still further preferred embodiment, the flexible plastic film material is any one of PET, PVC, and PC.

[0081] As Figure 9 shown, a specific embodiment of the fabrication of the uneven microstructured surface 02 on the base layer 01. The microstructured surface is fabricated according to the data calculated based on the theoretical basis: First, the microstructure data of the microstructured surface is transferred to a roller. The traditional method is to use a fast tool to press out the required structure, i.e., the imprinted structure 06, and then transfer the imprinted structure 06 to the soft mold structure 07, and finally transfer the required microstructure to our base layer 01 through UV transfer. Here, the material of the base layer 01 we selected is mainly polyester film, such as PET. From Figure 9 it can be seen that through this process, finally, the microstructured surface 02 on the base layer 01 has good conformal with the pressed-out structure. The single microstructured surface has a micron-scale size in terms of scale, and usually the diameter of the microstructure is within 50 um.

[0082] The reflective layer 03 on the surface of the base layer 01 can usually be made by magnetron sputtering. Compared with evaporation coating, magnetron sputtering has better control over thickness and uniformity. When the reflective layer 03 is a metal layer, in order to enhance the adhesion between the metal layer and the microstructured surface, we can first sputter a layer of adhesion promotion layer, such as silicon dioxide, the thickness of silicon dioxide is between 10nm and 100nm; the metal layer can usually be made of aluminum, silver, or one or more of other metals and metal oxides, halides, and nitrides. According to different metal materials, we choose different coating thicknesses, such as aluminum, the coating thickness is usually controlled at 20nm to 50nm; in order to prevent oxidation of the metal layer, we will also coat an anti-oxidation layer on the outside of the metal layer, such as: silicon dioxide, titanium dioxide, ITO, etc. Based on the current advanced manufacturing equipment, the entire process can be produced using a roll-to-roll process.

[0083] In order to effectively protect the surface of the high polarization-maintaining optical film before use, we will set a covering layer 04 on the surface of the high polarization-maintaining optical film after the preparation of the high polarization-maintaining optical film is completed, and then use laser to punch the high polarization-maintaining optical film to form holes 05 and splice, and then remove the protective layer after the final hanging to ensure the integrity of the high polarization-maintaining optical film surface and the viewing effect.

[0084] Although the present application mainly describes the implementation scheme of the present invention with a two-layer (base layer 01 and reflective layer 03) core structure, those skilled in the art should understand that within the protection scope of the present invention, it is not excluded that other layers besides the covering layer 04 may be present on any side of the high polarization-maintaining optical film, such as: a bonding layer, an adhesive layer, a reinforcing layer, an anti-reflection layer, an absorption layer, an anti-reflection layer, etc., and those skilled in the art should understand that these layers can be understood as part of the base layer 01 or the reflective layer 03.

[0085] In addition, those skilled in the art should understand that within the protection scope of the present invention, it is not excluded that other layers besides the adhesion promoting layer and the anti-oxidation layer may be present between the two layers (base layer 01 and reflective layer 03) of the high polarization-maintaining optical film, such as: a bonding layer, an adhesive layer, a reinforcing layer, an anti-reflection layer, an absorption layer, an anti-reflection layer, etc., and those skilled in the art should understand that these layers may be understood as part of the base layer 01 or the reflective layer 03.

[0086] To achieve the above object, the present application also provides a projection screen, which includes: a frame, an optical film, and an elastic structure. The frame is made of metal or plastic material; the optical film is composed of multiple pieces of the above-mentioned high polarization-maintaining optical films and is spliced together with glue; the elastic structure stretches the optical film reasonably and fixes it on the frame. As a preferred embodiment of the present application, the elastic structure is a spring. As a preferred embodiment of the present application, the optical film has holes 05 formed by laser drilling.

[0087] In summary, the present invention provides a specially designed high polarization-maintaining optical film. In the high polarization-maintaining optical film, the upper surface of the base layer 01 is designed as an uneven microstructured surface 02, and a reflective layer 03 that is substantially conformal with the upper surface 014 of the base layer is designed on the upper surface 014 of the base layer, so that the upper surface 032 of the reflective layer forms a microstructured surface that is basically consistent with the upper surface 014 of the base layer. This high polarization-maintaining optical film has excellent polarization direction retention, reflectivity, gain, and viewing angle performance; it can produce a high polarization-maintaining and high-definition picture quality screen, and at the same time can solve the problem of high cost of existing products, which is beneficial to the promotion of the 3D movie market. In addition, the high polarization-maintaining optical film of the present application can be applied not only to the theater movie market, but also to home theaters, science and technology museums, and other exhibition halls.

[0088] Although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0089] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A highly polarization-maintaining optical film, characterized in that, The high polarization-maintaining optical film includes: A base layer (01), the base layer (01) having a lower surface (013) of the base layer and an upper surface (014) of the base layer opposite to the lower surface (013) of the base layer. The upper surface (014) of the base layer is an uneven microstructured surface (02), and a reflective layer (03) provided on the base layer (01). The reflective layer (03) has a lower surface (031) of the reflective layer and an upper surface (032) of the reflective layer opposite to the lower surface (031) of the reflective layer. The lower surface (031) of the reflective layer is disposed on the upper surface (014) of the base layer. The reflective layer (03) is substantially conformal to the upper surface (014) of the base layer, so that the upper surface (032) of the reflective layer forms a microstructured surface substantially consistent with the upper surface (014) of the base layer; Wherein, the cross-section of the uneven microstructured surface (02) is an arc structure, and the angle θ between the tangent line of any point on the upper surface (032) of the reflective layer and the plane parallel to the lower surface (013) of the base layer is controlled to randomly vary between 0 degrees and + / - 30 degrees; the probability of the angle θ between the tangent line of any point on the upper surface (032) of the reflective layer and the plane parallel to the lower surface (013) of the base layer appears continuously varies with the angle of the angle θ; When the σ angle is equal to 40° and 20° respectively, the depth-to-width ratios of the arcs of the corresponding microstructured surfaces are 20:3 and 10:1 respectively. The σ angle is half of the reflection angle. The total reflectivity of the high polarization-maintaining optical film reaches more than 95%, the vertical polarization contrast ratio is greater than 1000:1, the gain is between 1.3 - 3.5, and the viewing angle is controlled between ±20° and ±50°.

2. The highly polarization-maintaining optical film according to claim 1, wherein Optionally, in any region with a dimension greater than 1 mm along the direction parallel to the lower surface (013) of the base layer, the structure of the upper surface (032) of the reflective layer is composed of at least two wave peaks and at least two wave valleys, and the wave peaks and wave valleys have a random structure.

3. The highly polarization-maintaining optical film according to claim 2, wherein The probability of the angle θ appearing at 0 degrees is the largest, and the probability of the angle θ appearing continuously decreases as the absolute value of the angle increases.

4. The highly polarization-maintaining optical film according to claim 3, wherein The ratio of the maximum value to the minimum value of the probability of the angle θ appearing is less than 10:

1.

5. The highly polarization-maintaining optical film according to claim 3, characterized in that, The ratio of the maximum value to the minimum value of the probability of the angle θ appearing is less than 2:

1.

6. The highly polarization-maintaining optical film according to claim 1, wherein, The characteristic length L between adjacent wave peaks or adjacent wave valleys of the reflective layer (03) is not greater than 0.5 mm.

7. The highly polarization-maintaining optical film according to claim 1, wherein The characteristic length L between adjacent wave peaks or adjacent wave valleys of the reflective layer (03) is not greater than 0.05 mm.

8. The highly polarization-maintaining optical film according to claim 1, wherein The height difference between the wave peaks and wave valleys on the upper surface (032) of the reflective layer is not greater than 100 µm.

9. The highly polarization-maintaining optical film according to claim 1, characterized in that, The height difference between the wave peaks and wave valleys on the upper surface (032) of the reflective layer is not greater than 10 µm.

10. The highly polarization-maintaining optical film according to claim 1, wherein The reflective layer (03) is composed of multiple layers of media, and the coherent superposition of the reflected light (003) of the multiple layers of interfaces is used to achieve high reflection of the incident light (001).

11. The highly polarization-maintaining optical film according to claim 1, wherein The reflective layer (03) is formed by alternately stacking two isotropic optical transparent materials with different refractive indices.

12. The highly polarization-maintaining optical film according to claim 1 or 10 or 11, characterized in that, The reflective layer (03) is a metal layer.

13. The highly polarization-maintaining optical film according to claim 12, wherein The thickness of the metal layer is 5 nm to 1 µm.

14. The highly polarization-maintaining optical film according to claim 12, wherein The thickness of the metal layer is 20 nm to 50 nm.

15. The highly polarization-maintaining optical film according to claim 12, wherein The metal layer is prepared from at least one of silver, aluminum, and gold.

16. The highly polarization-maintaining optical film according to claim 12, characterized in that, The metal layer is prepared by any one of magnetron sputtering and evaporation coating processes.

17. The highly polarization-maintaining optical film according to claim 12, characterized in that, An adhesion promoting layer is provided between the uneven microstructured surface (02) and the metal layer.

18. The highly polarization-maintaining optical film according to claim 17, wherein, The adhesion promoting layer is prepared from silicon dioxide.

19. The highly polarization-maintaining optical film according to claim 18, wherein, The thickness of the silicon dioxide is 10 nm to 100 nm.

20. The highly polarization-maintaining optical film according to claim 17, wherein The adhesion promoting layer is prepared by any one of magnetron sputtering and evaporation coating processes.

21. The highly polarization-maintaining optical film according to claim 12, wherein An antioxidant layer is provided on the surface of the metal layer.

22. The highly polarization-maintaining optical film according to claim 21, wherein The antioxidant layer is prepared from any one of materials including silicon dioxide, titanium dioxide, and ITO.

23. The highly polarization-maintaining optical film according to claim 21, wherein, The antioxidant layer is prepared by any one of magnetron sputtering and evaporation coating processes.

24. The highly polarization-maintaining optical film according to claim 1 or 17 or 21, characterized in that, The high polarization maintaining optical film further includes a cover layer (04), the cover layer (04) having a lower surface of the cover layer and an upper surface of the cover layer opposite to the lower surface of the cover layer, and the lower surface of the cover layer is disposed on the upper surface (032) of the reflective layer.

25. The highly polarization-maintaining optical film according to claim 1, wherein, The uneven microstructured surface (02) is prepared by any one of processes including fast tool imprinting, surface cutting, surface etching, and sandblasting.

26. The highly polarization-maintaining optical film according to claim 1, wherein The material of the base layer (01) is a deformable flexible plastic film material.

27. The highly polarization-maintaining optical film according to claim 26, wherein The flexible plastic film material is any one of PET, PVC, and PC.

28. A projection screen, characterized in that, The projection screen includes: A frame, an optical film, and an elastic structure: The frame is made of a metal or plastic material; The optical film is composed of multiple high polarization maintaining optical films according to any one of claims 1 - 27 and is spliced by glue; The elastic structure reasonably stretches the optical film and fixes it on the frame.

29. The projection screen according to claim 28, wherein The elastic structure is a spring.

30. The projection screen according to claim 28, wherein, The optical film has holes (05) formed by laser drilling.

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