Optical structure, method of manufacturing the same, and display device

Abstract

An optical structure, a manufacturing method thereof, and a display device. The optical structure includes an optical element and a light-transmitting protective film. The optical element includes a first surface and a second surface; the light-transmitting protective film is located between the optical element and air and is in contact with the optical element. The optical element includes a lens structure, a transmission-reflection film, a reflective polarizing film, and a phase retardation film; the lens structure includes a first lens surface and a second lens surface; the first surface and the second surface include at least one of a surface of the transmission-reflection film, a surface of the phase retardation film, a surface of the reflective polarizing film, the first lens surface, and the second lens surface; the light-transmitting protective film includes a first structure and a second structure; the second structure is in contact with air; the first structure is in contact with the optical element; the compactness of the first structure is greater than that of the second structure; the second structure includes a plurality of microstructures; and the pitch of the microstructures is not greater than the working wavelength of the optical element. The light-transmitting protective film has the effects of isolating external water and oxygen and reducing reflection.

Description

Technical Field

[0001] This disclosure relates to an optical structure, a method for manufacturing the same, and a display device. Background Technology

[0002] Optical components, such as optical lens groups, waveguides, and prisms, may include various components such as micro / nano structures, optical resins, optical thin films, optical adhesives, and optical coatings, as well as various organic polymers, small organic molecules, metals, and inorganic non-metallic materials to meet specific and complex optical requirements. The high water absorption rate of certain optical resins (such as polymethyl methacrylate, PMMA), the fogging or delamination phenomena of certain optical adhesives or resins when exposed to moisture, the tendency to release gas and form bubbles when exposed to high temperature and humidity, and the corrosion characteristics of certain metallic materials and small molecule materials in coatings when exposed to moisture and oxygen are all closely related to the moisture and oxygen in the external environment. Therefore, an important way to improve the reliability of optical components is to isolate them from the external water and oxygen environment. Summary of the Invention

[0003] This disclosure provides an optical structure, a method for manufacturing the same, and a display device.

[0004] This disclosure provides an optical structure including an optical element and a light-transmitting protective film. The optical element includes a first surface and a second surface disposed opposite to each other; the light-transmitting protective film is located between the optical element and air, and the light-transmitting protective film is in contact with at least one of the first surface and the second surface. The optical element includes a lens structure and a transflective coating, a reflective polarizing coating, and a phase retardation coating disposed on the lens structure. The lens structure includes a first lens surface and a second lens surface located on its light-incident and light-out sides, respectively. At least one of the first lens surface and the second lens surface is a curved surface. The reflective polarizing coating and the phase retardation coating are both located on the side of the transflective coating facing the second lens surface. The first surface and the second surface include at least one of the surface of the transflective coating, the surface of the phase retardation coating, the surface of the reflective polarizing coating, the first lens surface, and the second lens surface. The light-transmitting protective film includes a first structure and a second structure stacked together. The second structure is in contact with the air, and the first structure is in contact with the optical element. The density of the first structure is greater than that of the second structure. The second structure includes a plurality of microstructures, and the pitch of at least some of the microstructures in a direction parallel to the surface of the first structure in contact with the optical element is a characteristic dimension. The characteristic dimension is not greater than the operating wavelength of the optical element.

[0005] For example, according to an embodiment of this disclosure, the water vapor permeability coefficient of the material of the first structure is ≤1 g·mm / (m 2 •24h).

[0006] For example, according to an embodiment of this disclosure, the feature size of the second structure is 10 to 300 nanometers.

[0007] For example, according to embodiments of this disclosure, the average thickness of the light-transmitting protective film is 50 nanometers to 10 micrometers.

[0008] For example, according to an embodiment of this disclosure, the average thickness of the second structure is 20 to 300 nanometers.

[0009] For example, according to an embodiment of this disclosure, the refractive index of the first structure is greater than the equivalent refractive index of the second structure, the refractive index of the first structure is 1.4 to 2.5, and the equivalent refractive index of the second structure gradually decreases along the arrangement direction from the first structure to the second structure.

[0010] For example, according to an embodiment of this disclosure, the dimension of each microstructure in a direction parallel to the surface of the first structure in contact with the optical element is a cross-sectional dimension, and the cross-sectional dimension of the at least some microstructures gradually decreases along the arrangement direction.

[0011] For example, according to embodiments of this disclosure, the shape of at least a portion of the microstructure includes a frustum or a cone.

[0012] For example, according to embodiments of this disclosure, the material of the light-transmitting protective film includes one or more of parylene and its various substituted derivatives, hexamethyldisiloxane, polytetrafluoroethylene, acrylic acid, and fluorosilane.

[0013] For example, according to an embodiment of this disclosure, the second structure in the light-transmitting protective film is configured to have a reflectivity of less than 0.2% for visible light.

[0014] For example, according to an embodiment of this disclosure, the light-transmitting protective film completely surrounds the optical element.

[0015] For example, according to an embodiment of this disclosure, the first structure and the second structure are an integrated structure.

[0016] For example, according to an embodiment of this disclosure, the optical structure further includes a linear polarizing film located on the side of the reflective polarizing film away from the transmissive film.

[0017] For example, according to an embodiment of this disclosure, the second surface includes the linearly polarizing film.

[0018] This disclosure provides a display device, including a display screen and the aforementioned optical structure, wherein the optical structure is located on the display side of the display screen, and the second surface is located on the side of the first surface away from the display screen.

[0019] This disclosure provides a method for fabricating the above-described optical structure, comprising: forming the plurality of microstructures in the light-transmitting protective film using a plasma etching method.

[0020] In the optical structure provided in this disclosure, a light-transmitting protective film is provided on at least one of the first and second surfaces of an optical element including a lens structure, a transflective film, a reflective polarizing film, and a phase retardation film. The second structure of the light-transmitting protective film in contact with air includes a microstructure with a feature size not greater than the operating wavelength. This ensures that while the environmentally sensitive optical element is isolated from external water and oxygen by the light-transmitting protective film, the optical performance of the optical element is not degraded by the addition of the light-transmitting protective film. Furthermore, the light-transmitting protective film has anti-reflective properties. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure.

[0022] Figure 1 This is a cross-sectional schematic diagram of an optical structure provided according to an example embodiment of the present disclosure.

[0023] Figure 2 for Figure 1 An enlarged view of region A shown.

[0024] Figure 3 This is a cross-sectional schematic diagram of an optical structure provided according to another example of an embodiment of the present disclosure.

[0025] Figure 4 This is a partial cross-sectional structural schematic diagram of a display device provided according to another embodiment of the present disclosure. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the described embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0027] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that an element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0028] The features such as "parallel," "perpendicular," and "identical" used in the embodiments of this disclosure include features in the strict sense of "parallel," "perpendicular," and "identical," as well as cases where "approximately parallel," "approximately perpendicular," and "approximately identical" include certain errors, taking into account measurement and errors associated with the measurement of a specific quantity (e.g., limitations of the measurement system), and represent the acceptable deviation range for a specific value as determined by a person skilled in the art. For example, "approximately" can mean within one or more standard deviations, or within 10% or 5% of said value. Unless otherwise specified in the embodiments of this disclosure, the quantity of a component is implied to mean that the component can be one or more, or can be understood as at least one. "At least one" means one or more, and "more" means at least two.

[0029] Common methods for isolating components exposed to air from water and oxygen include forming a conformal coating on the component surface. This involves applying or depositing at least one dense coating / plating layer on the component surface to block external water and oxygen. Currently, conformal coatings are used for waterproofing circuit boards, chips, microelectromechanical systems (MEMS), magnetic cores, sensors, optical fibers, and mobile phone exteriors in the electronics industry. These conformal coatings can include coatings such as parylene, hexamethyldisiloxane (HMDSO), polytetrafluoroethylene (PTFE), and fluorosilanes deposited using chemical vapor deposition (CVD), or coatings such as acrylic, polyurethane, and silicone conformal coatings applied using solution methods.

[0030] An optical element for use in the field of virtual reality (VR) includes a structure with a short focal length folded optical path (pancake), such as multiple lenses made of optical resin, organic and inorganic optical coatings and platings coated on the lens surface, polymer films attached to the lens surface by optical adhesive film (OCA) or pressure-sensitive optical adhesive (PSA), such as reflective polarizing film, phase retardation film, liquid crystal compensation film, linear polarizing film, antireflection film, etc., and optical adhesive resin (OCR) for bonding multiple lenses.

[0031] There are various methods for isolating optical components from water and oxygen environments. However, for the aforementioned pancake-structured optical components, which need to be in contact with both the human eye and the display screen, air will be present around the optical components, making it impossible to completely seal them within a packaging mechanism. Furthermore, for the aforementioned precision optical components with pancake structures, if the aforementioned coating is directly deposited onto the optical surface, the coating will generally significantly alter the optical performance of the optical component. Even if the aforementioned coating is deposited first and then the anti-reflective coating is applied, the original optical performance of the optical component cannot be maintained because there is still abrupt optical interface between the traditional anti-reflective coating and the coating.

[0032] In their research, the inventors of this application discovered that traditional antireflective coatings with multiple layers have limited antireflective effects, especially on resin lenses and polymers commonly used in protective coatings. The number of antireflective layers and the materials used in these coatings are limited, making it impossible to offset the interference of the added surface layer on the optical element's performance. For optical elements with a pancake structure, or those including multi-lens assemblies, adding a protective coating while maintaining their original optical performance requires a high level of antireflective performance. Currently, antireflective methods that may meet these high requirements include structural antireflective methods and moth-eye antireflective methods. Structural antireflective methods include subwavelength structured coating (SWC), which involves first depositing a hydrolyzable material, such as alumina, onto the optical element using atomic layer deposition (ALD) or physical vapor deposition (PVD). The optical element with the deposited film is then immersed in water or a suitable solvent, causing the film to hydrolyze into a loose, porous structure. This results in a film with a suitable low refractive index or gradient refractive index, achieving a better antireflective effect. While this structural anti-reflection method is already mass-producible, its yield, production capacity, and cost are extremely limited. Furthermore, due to the hydrolysis process, it may corrode optical components, contradicting the technical problem this application aims to solve. The moth-eye anti-reflection method involves first forming the anti-reflection structure on a transparent plastic foil using roll-to-roll nanoimprinting, and then attaching the plastic foil to the lens surface. However, this method is unsuitable for anti-reflection requirements on lens surfaces with large curvatures, and its high cost may introduce new reliability risks.

[0033] Therefore, neither of the above two anti-reflection methods can adequately compensate for the deterioration of optical performance in pancake-structured optical elements after adding a conformal coating for protection.

[0034] This disclosure provides an optical structure, a method for manufacturing the same, and a display device. The optical structure includes an optical element and a light-transmitting protective film. The optical element includes a first surface and a second surface disposed opposite to each other; the light-transmitting protective film is located between the optical element and air, and the light-transmitting protective film is in contact with at least one of the first surface and the second surface. The optical element includes a lens structure and a transflective coating, a reflective polarizing coating, and a phase retardation coating disposed on the lens structure. The lens structure includes a first lens surface and a second lens surface located on its light-incident side and light-out side, respectively. At least one of the first lens surface and the second lens surface is a curved surface. The reflective polarizing coating and the phase retardation coating are both located on the side of the transflective coating facing the second lens surface. The first surface and the second surface include at least one of the surface of the transflective coating, the surface of the phase retardation coating, the surface of the reflective polarizing coating, the first lens surface, and the second lens surface. The light-transmitting protective film includes a first structure and a second structure stacked together. The second structure is in contact with air, and the first structure is in contact with the optical element. The density of the first structure is greater than that of the second structure. The second structure includes multiple microstructures. The pitch of at least some of the microstructures in the direction parallel to the surface of the first structure in contact with the optical element is a characteristic dimension. The characteristic dimension is not greater than the operating wavelength of the optical element.

[0035] In the optical structure provided in this disclosure, a light-transmitting protective film is provided on at least one of the first and second surfaces of an optical element including a lens structure, a transflective film, a reflective polarizing film, and a phase retardation film. The second structure of the light-transmitting protective film in contact with air includes a microstructure with a feature size not greater than the operating wavelength. This ensures that while the environmentally sensitive optical element is isolated from external water and oxygen by the light-transmitting protective film, the optical performance of the optical element is not degraded by the addition of the light-transmitting protective film. Furthermore, the light-transmitting protective film has anti-reflective properties.

[0036] The optical structure, its manufacturing method, and the display device provided in this disclosure are described below with reference to the accompanying drawings.

[0037] Figure 1 This is a cross-sectional schematic diagram of an optical structure provided according to an example embodiment of the present disclosure. Figure 2 for Figure 1 An enlarged view of region A shown.

[0038] like Figure 1 As shown, the optical structure includes an optical element 10 and a light-transmitting protective film 20. The optical element 10 includes a first surface 11 and a second surface 12 disposed opposite each other. The light-transmitting protective film 20 is located between the optical element 10 and air, and the light-transmitting protective film 20 is in contact with at least one of the first surface 11 and the second surface 12. For example, the light-transmitting protective film 20 is configured to protect at least a portion of the structure of the optical element 10. For example, the surface of the light-transmitting protective film 20 away from the optical element 10 can be in contact with air.

[0039] like Figure 1 As shown, the optical element 10 includes a lens structure 100 and a transflective coating 200, a reflective polarizing coating 300, and a phase retardation coating 400 disposed on the lens structure 100. The lens structure 100 includes a first lens surface 111 and a second lens surface 112 located on its light-incident side and light-outcident side, respectively. At least one of the first lens surface 111 and the second lens surface 112 is a curved surface.

[0040] For example, such as Figure 1 As shown, the first lens surface 111 and the second lens surface 112 are the two outermost opposing surfaces of the lens structure 100. For example, the lens structure 100 may include at least one lens, such as a lens lens. The first lens surface 111 and the second lens surface 112 may be two surfaces of the same lens, or they may be surfaces of different lenses. For example, both the first lens surface 111 and the second lens surface 112 may be curved surfaces; for example, the first lens surface 111 may be convex, and the second lens surface 112 may be concave, but this is not limited to these; only one of the first lens surface 111 and the second lens surface 112 may be curved. For example, at least one of the first lens surface 111 and the second lens surface 112 may be a spherical surface, an aspherical surface, or a freeform surface. For example, the radius of curvature of at least one of the first lens surface 111 and the second lens surface 112 may not exceed 20 mm.

[0041] like Figure 1 As shown, both the reflective polarizing film 300 and the phase retardation film 400 are located on the side of the transflective film 200 facing the second lens surface 112. For example, the reflective polarizing film 300 is located on the side of the phase retardation film 400 away from the transflective film 200. Of course, the embodiments of this disclosure are not limited to this, and the relative positional relationship between the reflective polarizing film 300 and the phase retardation film 400 can be set according to different material selections.

[0042] In some examples, such as Figure 1 As shown, the optical structure also includes a linear polarizing film 500 located on the side of the reflective polarizing film 300 away from the transmissive film 200.

[0043] For example, such as Figure 1 As shown, the lens structure 100 includes three lenses, such as those along the optical axis OA parallel to the lens structure 100 (e.g., ...). Figure 1Lenses 101, 102, and 103 are sequentially arranged in the X direction (as shown in the image). The surface of lens 101 away from lens 102 can be a first lens surface 111, and the surface of lens 103 away from lens 102 can be a second lens surface 112. Adjacent lenses are bonded together with optically transparent adhesive (OCR). For example, the first lens surface 111 can be convex, the lens surface of lens 101 facing lens 102 can be concave, and the lens surface of lens 102 facing lens 101 can be convex, with these two lens surfaces having essentially the same shape. The lens surface of lens 102 away from lens 101 can be flat, and the lens surface of lens 103 facing lens 102 can be flat. The second lens surface 112 can be concave. For example, the first surface 11 and the second surface 12 of the optical element 10 are arranged in a direction parallel to the optical axis OA.

[0044] For example, such as Figure 1 As shown, the transflective coating 200, which can be called a semi-transflective coating, is deposited on the surface of lens 102 facing lens 101. For example, a phase retardation film 400 can be bonded between lens 102 and lens 103. A liquid crystal compensation film can also be provided between lens 102 and lens 103. For example, the phase retardation film 400 and the liquid crystal compensation film are bonded between lens 102 and lens 103 using pressure-sensitive adhesive (PSA). For example, a reflective polarizing film 300 and a linear polarizing film 500 are bonded to the second lens surface 112 on the side of lens 103 away from lens 102. For example, the reflective polarizing film 300 is bonded to the second lens surface 112 using optical adhesive (OCA).

[0045] For example, such as Figure 1 As shown, the lens structure 100 includes multiple zero-phase-difference lenses, such as lens 101, lens 102 and lens 103, which are zero-phase-difference lenses, and are made of acrylic material (PMMA).

[0046] For example, such as Figure 1As shown, the transflective film 200 is configured to transmit part of the light and reflect another part of the light. For example, the transflective film 200 may include at least one film layer, such as the thickness of each film layer being 10-200 nanometers. For example, the transmittance of the transflective film 200 may be 50%, and the reflectance may be 50%. For example, the transmittance of the transflective film 200 may be 60%, and the reflectance may be 40%. For example, the transmittance of the transflective film 200 may be 65%, and the reflectance may be 35%. The optical structure provided in this disclosure is not limited to this; the transmittance and reflectance of the transflective film 200 can be set according to product requirements. For example, the transflective film 200 can be deposited on the convex surface of the lens 102 by first applying a polysiloxane primer using spin coating or dip coating, and then deposited using ion-assisted evaporation coating to form a metal-containing transflective film 200. For example, the transflective film 200 includes a stacked metal layer and at least one non-metal layer. For example, the at least one non-metal layer has multiple layers, each located on both sides of the metal layer. For example, the transflective membrane 200 may include titanium dioxide (TiO2), silver (Ag), titanium dioxide (TiO2), silicon dioxide (SiO2), and titanium dioxide (TiO2) stacked sequentially. For example, the thicknesses of the aforementioned sequentially stacked titanium dioxide, silver, titanium dioxide, silicon dioxide, and titanium dioxide may be 29.7 nm, 18.2 nm, 1.5 nm, 16.1 nm, and 68.6 nm, respectively.

[0047] For example, such as Figure 1 As shown, the reflective polarizing film 300 can be a polarizing reflective film, which is configured to reflect linearly polarized light with one characteristic and transmit linearly polarized light with another characteristic.

[0048] For example, such as Figure 1 As shown, the reflective polarizing film 300 functions as follows: Within the plane of the film layer, there exists a transmission axis. The transmittance of the polarization component of incident light parallel to this transmission axis (e.g., s-polarized light) is greater than the transmittance of the polarization component perpendicular to this transmission axis (e.g., p-polarized light), and the reflectance of the polarization component parallel to this transmission axis (e.g., s-polarized light) is less than the reflectance of the polarization component perpendicular to this transmission axis (e.g., p-polarized light). For example, the reflective polarizing film 300 can also be called a polarizing beam splitter. For example, the transmittance of polarized light parallel to the transmission axis of the reflective polarizing film 300 is not less than 85%, and is not less than 90%, 95%, or 98%; the reflectance of polarized light perpendicular to the transmission axis of the reflective polarizing film 300 is not less than 85%, and is not less than 90%, 95%, or 98%. For example, the reflective polarizing film 300 may include multilayer reflective polarizing films, wire grid polarizers (WGF), etc.

[0049] For example, such as Figure 1As shown, the phase retardation film 400 is configured to enable the transmitted light to switch between circular and linear polarization states. For example, the phase retardation film 400 can be a quarter-wave plate. For example, the material of the phase retardation film 400 can include a liquid crystal polymer or polycarbonate. For example, the phase retardation film 400 has the following characteristics: there is a direction with the lowest refractive index and a direction with the highest refractive index within the film plane, which are the fast axis and the slow axis, respectively; the phase of polarized light parallel to the slow axis is delayed by 1 / 4 wavelength after passing through the phase retardation film 400 compared to the phase of polarized light parallel to the fast axis after passing through the phase retardation film 400.

[0050] For example, such as Figure 1 As shown, the angle between the slow axis of the phase retardation film 400 and the transmission axis of the reflective polarizing film 300 is 45 degrees.

[0051] For example, such as Figure 1 As shown, the transmission axis of the linear polarizing film 500 coincides with the transmission axis of the reflective polarizing film 300. The linear polarizing film 500 can be used to further filter out other stray light, allowing only polarized light (such as s-polarized light) that passes through it to enter the human eye. For example, the linear polarizing film 500 can be called a polarizer, composed of a triacetate cellulose (TAC) film and a stretched polyvinyl alcohol (PVA) film with added iodine molecules, bonded to the reflective polarizing film 300 via a PSA.

[0052] For example, such as Figure 1 As shown, the display screen ( Figure 1 Not shown, combined Figure 4 The display screen 30 can be located on the side of the transflective film 200 away from the phase retardation film 400. Light, such as light emitted from the display screen, is incident on the lens structure 100 after passing through the transflective film 200, and is configured to be reflected back between the transflective film 200 and the reflective polarizing film 300, and then exit from the reflective polarizing film 300 to achieve an ultra-short focal length folded optical path (Pancake). For example, image light emitted from the display screen 30 passes through the first lens surface 111 on the light-incident side of the lens structure 100 and then enters the lens structure 100. After being reflected back, it exits from the second lens surface 112 on the light-outceasing side of the lens structure 100.

[0053] For example, such as Figure 1As shown, the principle of the folded optical path is as follows: A waveplate can be set on the light-emitting side of the display screen 30. The image light emitted from the display screen 30 is converted into right-hand circularly polarized light after passing through the waveplate. The right-hand circularly polarized light is incident on the transmission-reflection film 200. After being transmitted through the transmission-reflection film 200, the polarization state of the right-hand circularly polarized light remains unchanged. This right-hand circularly polarized light reaches the phase retardation film 400, where it is converted into p-linearly polarized light. The p-linearly polarized light is reflected back to the phase retardation film 400 by the reflective polarizing film 300, where the first reflection occurs. Then, the p-linearly polarized light is converted into right-hand circularly polarized light after passing through the phase retardation film 400. This right-hand circularly polarized light reaches the transmission-reflection film 200 and is reflected at the transmission-reflection film 200, where the second reflection occurs. Due to half-wave loss, the reflected light changes from right-hand circularly polarized light to left-hand circularly polarized light. Left-handed circularly polarized light is converted into s-linearly polarized light by phase retardation film 400, and then the s-linearly polarized light is transmitted to the human eye after passing through reflective polarization film 300 and linear polarization film 500.

[0054] The aforementioned folded optical path can change the polarization state of the light propagating between the reflective polarizing film 300 and the transmissive film 200, thereby folding the light. This causes the focal length of the optical element 10, which would otherwise be increased by, for example, two reflections due to the presence of the reflective polarizing film 300, the phase retardation film 400, and the transmissive film 200, to be folded. This greatly reduces the space required between the human eye and the optical structure, making the optical element 10 smaller and thinner.

[0055] like Figure 1 As shown, the first surface 11 and the second surface 12 of the optical element 10 include at least one of the surfaces of the transflective coating 200, the phase retardation film 400, the reflective polarizing film 300, the first lens surface 111, and the second lens surface 112. For example, the first surface 11 and the second surface 12 of the optical element 10 include at least one of the surfaces of the transflective coating 200, the phase retardation film 400, the reflective polarizing film 300, the linear polarizing film 500, the first lens surface 111, and the second lens surface 112. For example, Figure 1 The first surface 11 of the optical element 10 is schematically shown as the first lens surface 111 of the lens structure 100.

[0056] In some examples, such as Figure 1 As shown, the second surface 12 of the optical element 10 includes a linear polarizing film 500.

[0057] like Figure 1 and Figure 2As shown, the light-transmitting protective film 20 includes a first structure 21 and a second structure 22 stacked together. The second structure 22 is in contact with air, and the first structure 21 is in contact with the optical element 10. The density of the first structure 21 is greater than that of the second structure 22. The second structure 22 includes a plurality of microstructures 221. At least some of the microstructures 221 have a characteristic dimension of pitch P1 in a direction parallel to the surface of the first structure 21 in contact with the optical element 10. The characteristic dimension is not greater than the operating wavelength of the optical element 10.

[0058] When the optical element 10 provided in this embodiment is not protected by the light-transmitting protective film 20, the PMMA-based lens structure 100 has a high water absorption rate. Under high temperature and high humidity conditions, water absorption will cause failure between the lens and the coating in the lens structure 100. The silver in the transflective film 200 is easily corroded by the external water and oxygen environment. The PVA in the linear polarizing film 500 is easy to absorb moisture, and moisture can easily interfere with the molecular arrangement and reaction with iodine molecules, leading to material failure. Under high temperature and high humidity conditions, the OCA, PSA and OCR may fog up due to condensation after water absorption saturation, or generate bubbles due to water absorption and gas release.

[0059] In the optical structure provided in this disclosure, a light-transmitting protective film 20 is provided on at least one of the first surface 11 and the second surface 12 of the optical element 10, which includes a lens structure 100, a transmissive film 200, a reflective polarizing film 300, and a phase retardation film 400. The second structure 22 of the light-transmitting protective film 20 in contact with air includes a microstructure 221 with a feature size not greater than the operating wavelength. This ensures that the optical element 10, which is sensitive to the environment, is isolated from external water and oxygen by the light-transmitting protective film 20, while the optical performance of the optical element is not affected by the addition of the light-transmitting protective film. The light-transmitting protective film also has anti-reflective properties.

[0060] For example, the aforementioned density refers to the amount of air content in a substance. If the substance contains a large amount of air, its density is low; if the substance contains a small amount of air, its density is high. For example, the statement that the density of the first structure 21 is greater than that of the second structure 22 can mean that the air content in the first structure 21 is lower than that in the second structure 22.

[0061] For example, such as Figure 2 As shown, the first structure 21 can be referred to as a continuous dense structure, and the second structure 22 can be referred to as a discontinuous structure. For example, in the discontinuous structure, air is provided between adjacent microstructures 221 in a cross-section cut by a plane parallel to the first surface 11. By setting the first structure 21 as a continuous dense structure, the light-transmitting protective film 20 can achieve barrier properties against water vapor and oxygen.

[0062] In some examples, such as Figure 2As shown, the water vapor permeability coefficient of the material of the first structure 21 is ≤1 g·mm / (m 2 •24h). For example, the water vapor transmission coefficient of the material of the second structure 22 is greater than that of the material of the first structure 21. The above 1 g·mm / (m 2 •24h) indicates the mass of water vapor that permeates per unit area and unit thickness of the first structure 21 per unit time under specific conditions (temperature, humidity, etc.), such as the first structure 21 with a thickness of 1 mm per square meter is allowed to pass no more than 1 gram of water vapor in 24 hours.

[0063] For example, such as Figure 2 As shown, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.9 g·mm / (m 2 •24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.8 g·mm / (m 2 (24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.7 g·mm / (m). 2 (24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.6 g·mm / (m). 2 (24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.5 g·mm / (m). 2 (24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.4 g·mm / (m). 2 •24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.3 g·mm / (m 2 •24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.2 g·mm / (m 2 •24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.1 g·mm / (m 2 (24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is ≤0.09 g·mm / (m). 2 (24h). For example, the water vapor permeability coefficient of the material of the first structure 21 is 0.08 g·mm / (m). 2 •24h).

[0064] In some examples, such as Figure 1As shown, the light-transmitting protective film 20 completely surrounds the optical element 10. For example, the light-transmitting protective film 20 is in contact with the outer surface of the optical element 10 at various locations. For example, in addition to the first surface 11 and the second surface 12 that are opposite to each other, the optical element 10 also includes other surfaces located between them, such as surfaces parallel to the optical axis OA, such as the contour surfaces of lens 101, lens 102, and lens 103, and the light-transmitting protective film 20 surrounds the above three contour surfaces. The light-transmitting protective film 20 completely surrounds the optical element 10, which can completely isolate the optical element 10 from external water and oxygen, and prevent the optical element 10 from failing due to water absorption by the materials of the lens structure 100, the silver in the transflective coating 200, the PVA, OCA, PSA and OCR in the linear polarizing film 500.

[0065] For example, Figure 2 A schematic cross-sectional view of the plurality of microstructures 221 included in the second structure 22 is shown. For example, the plurality of microstructures 221 may be arranged in an array along the first surface 11 of the optical element 10. For example, the plurality of microstructures 221 may be arranged at equal intervals, but are not limited thereto, and the spacing between the microstructures 221 at different positions may be adjusted according to the imaging area of ​​the optical element 10.

[0066] For example, such as Figure 2 As shown, the pitch P1 of the multiple microstructures 221 in the direction parallel to the surface of the first structure 21 that contacts the optical element 10 is a characteristic dimension. For example, the pitch P1 can be the distance between the center lines of two adjacent microstructures 221. For example, the pitch P1 can be the bottom surface of two adjacent microstructures 221 closest to the first structure 21 (e.g., Figure 2 The distance between the midpoints of the plane containing the boundary line B1 between the first structure 21 and the second structure 22 shown.

[0067] In some examples, such as Figure 2 As shown, the feature size is 10–300 nanometers. For example, the feature size is 12–280 nanometers. For example, the feature size is 15–250 nanometers. For example, the feature size is 20–220 nanometers. For example, the feature size is 25–200 nanometers. For example, the feature size is 30–170 nanometers. For example, the feature size is 35–150 nanometers. For example, the feature size is 40–120 nanometers. For example, the feature size is 50–100 nanometers. For example, the feature size is 55–80 nanometers. For example, the feature size is 60–70 nanometers. For example, the feature size is 65–155 nanometers. For example, the feature size is 45–180 nanometers. For example, the feature size is 75–160 nanometers. For example, the feature size is 85–270 nanometers. For example, the feature size is 110–260 nanometers. For example, the feature size is 120–240 nanometers.

[0068] It should be noted that the aforementioned feature dimensions are relatively small. Even if the surface of the first structure 21 that contacts the optical element 10 is curved, the direction parallel to the surface of the first structure 21 that contacts the optical element 10 can still be a straight line, such as... Figure 2 Y direction shown.

[0069] For example, the operating wavelength includes at least wavelengths in the visible light band. For example, the operating wavelength may include wavelengths in the visible light band and wavelengths in the infrared band. For example, the operating wavelength may include wavelengths in the near-infrared band. For example, the operating wavelength may be 380 nm to 1050 nm. For example, the operating wavelength may be 400 nm to 800 nm.

[0070] In some examples, such as Figure 1 and Figure 2 As shown, the material of the light-transmitting protective film 20 includes one or more of parylene and its various substituted derivatives, hexamethyldisiloxane (HMDSO), polytetrafluoroethylene (PTFE), acrylics, and fluorosilanes. For example, the material of the light-transmitting protective film 20 includes polychloroparylene (Parylene C), with a thickness of 500 nanometers, wherein the water vapor transmission coefficient of the material of the first structure 21 is 0.08 g·mm / (m). 2 •24h). For example, a light-transmitting protective film 20 can be formed on the optical element 10 by methods such as chemical vapor deposition, physical vapor deposition, or wet coating.

[0071] For example, such as Figure 2 As shown, the first structure 21 and the second structure 22 can be made of the same material, but are not limited thereto; the first structure 21 and the second structure 22 can also be formed of different materials.

[0072] In some examples, such as Figure 2 As shown, the first structure 21 and the second structure 22 are an integrated structure. The second structure 22 is formed by first forming a light-transmitting material layer on the optical element 10, and then patterning part of the thickness of the light-transmitting material layer.

[0073] In some examples, such as Figure 1 and Figure 2 As shown, the average thickness of the light-transmitting protective film 20 is 50 nanometers to 10 micrometers. The average thickness of the light-transmitting protective film 20 can be any value from 50 nanometers to 10 micrometers, for example, 70 nanometers, 7 micrometers, 8 micrometers, 100 nanometers or 5 micrometers, etc., and the embodiments disclosed herein are not limited thereto.

[0074] In some examples, such as Figure 2As shown, the average thickness of the second structure 22 is 20-300 nanometers. The average thickness of the second structure 22 can be any value between 20 nanometers and 300 nanometers, for example, 25 nanometers, 280 nanometers, 30 nanometers or 270 nanometers, etc., and the embodiments disclosed herein are not limited thereto.

[0075] For example, such as Figure 2 As shown, the average thickness of the first structure 21 is greater than the average thickness of the second structure 22, which is beneficial for providing better water and oxygen isolation protection for the optical element 10. Of course, the embodiments disclosed herein are not limited to this, and the average thickness of the first structure 21 may be less than the average thickness of the second structure 22.

[0076] For example, such as Figure 2 As shown, the average thickness of the light-transmitting protective film 20 is 500 nanometers, the average thickness of the second structure 22 is 120 nanometers, and the average thickness of the first structure 21 is 380 nanometers.

[0077] In some examples, such as Figure 2 As shown, the dimension of each microstructure 221 in the direction parallel to the surface of the first structure 21 in contact with the optical element 10 is its cross-sectional dimension. Along the arrangement direction from the first structure 21 to the second structure 22, the cross-sectional dimension of at least some microstructures 221 gradually decreases. By setting the shape of the microstructures 221, it is beneficial to adjust the effective refractive index of the second structure 22 to be between that of the first structure 21 and air, thereby reducing the reflectivity of the light-transmitting protective film 20 and achieving an anti-reflection effect that is difficult to achieve with general anti-reflection films.

[0078] For example, such as Figure 2 As shown, in the arrangement direction along the first structure 21 to the second structure 22, the area of ​​the cross section of each microstructure 221 cut by the surface parallel to the first lens surface 111 gradually decreases.

[0079] The arrangement direction of the first structure 21 pointing to the second structure 22 may include a direction perpendicular to the first lens surface 111, such as the normal of the first lens surface 111, or a direction parallel to the optical axis of the lens structure 100.

[0080] In some examples, such as Figure 2 As shown, at least some of the microstructures 221 have a shape including a frustum or a cone. For example, each microstructure 221 has the same shape, such as being a frustum or a cone.

[0081] Figure 2The microstructure 221 is schematically shown to be conical in shape. For example, the cross-sectional shape of the microstructure 221 can be triangular. For example, the triangle can be an isosceles triangle. Of course, the embodiments of this disclosure are not limited to this; when the shape of the microstructure 221 is a frustum, the cross-sectional shape of the microstructure 221 can be trapezoidal, such as an isosceles trapezoid. For example, the sides of the cross-section of the microstructure can be... Figure 2 The straight line shown can also be a curve, and this disclosure does not limit this.

[0082] In some examples, such as Figure 2 As shown, the refractive index of the first structure 21 is greater than the equivalent refractive index of the second structure 22. The refractive index of the first structure 21 is 1.4 to 2.5, and the equivalent refractive index of the second structure 22 gradually decreases along the alignment direction from the first structure 21 to the second structure 22. For example, the equivalent refractive index of the second structure 22 is between 1.1 and 1.4. For example, the equivalent refractive index of the second structure 22 is 1.2 to 1.3.

[0083] When the feature size of microstructure 221 is significantly smaller than the working wavelength of optical structure, the second structure 22 can be regarded as a mixture of air and film-forming material of light-transmitting protective film 20, and the equivalent refractive index of the second structure 22 is between the refractive index of the first structure 21 and the refractive index of air.

[0084] In some examples, such as Figure 2 As shown, the second structure 22 in the light-transmitting protective film 20 is configured to have a reflectivity of less than 0.2% for visible light. For example, the second structure 22 is configured to have a reflectivity of less than 0.1% for visible light. For example, the second structure 22 is configured to have a reflectivity of less than 0.05% for visible light.

[0085] For example, Figure 2 The following model applies when the thickness of the microstructure 221, which has a similar cone shape, is infinitesimally small:

[0086] (n2 2 -1) / [1+0.5 (n2 2 -1)]=p n1 2 / [1+0.5 (n1 2 -1)].

[0087] In the above-mentioned n2, n1 is the refractive index of the first structure 21, and p is the filling density of the dielectric material in the space occupied by the second structure 22. The thickness of the second structure 22 and p can be adjusted by controlling the etching process forming the second structure 22, thereby adjusting n2 and thus the reflectivity of the second structure 22 to visible light. For example, the second structure 22 can be made into a broadband antireflective film with an extremely low refractive index. This second structure 22 can not only minimize the impact of the light-transmitting protective film 20 on the optical performance of the optical element 10, but also achieve an antireflective effect that is difficult to achieve with general antireflective coatings.

[0088] For example, the second structure 22 can form a Cassie wetting state. When water droplets adhere to the surface of the second structure 22 away from the first structure 21, air is still retained between the microstructures 221 of the second structure 22, so that the surface of the transparent protective film forms a superhydrophobic state, and the transparent protective film has waterproof properties.

[0089] This disclosure provides a preparation method. Figure 1 and Figure 2 The method for fabricating the light-transmitting protective film shown employs plasma etching to form multiple microstructures 221 within the film. Of course, this disclosure is not limited to this embodiment, and the fabrication method is also applicable to subsequent applications. Figure 3 The light-transmitting protective film in the optical structure shown.

[0090] For example, plasma types include inductively coupled plasma (ICP), capacitively coupled plasma (CCP), bipolar plasma, radio frequency plasma, microwave plasma, etc., and etching gases can include argon (Ar), krypton (Kr), xenon (Xe), helium (He), oxygen (O2), hydrogen (H2), nitrogen (N2), carbon tetrafluoride (CF4), hydrogen fluoride (HF), sulfur hexafluoride (SF6), carbon hexafluoride (CF6), etc.

[0091] For example, Figure 2 After the optical element 10 is formed, a layer of polychloroparaxylene (Parylene C) film can be uniformly deposited on the surface of the optical element 10 using chemical vapor deposition. The water vapor transmission coefficient of the material is 0.08 g·mm / (m). 2• 24h), with a deposition thickness of 500 nm; using oxygen via inductively coupled plasma (ICP), the polychloroparaxylene film is etched to a depth of 120 nm into the air-facing surface, forming a second structure 22 with microstructure 221. When the porosity p of microstructure 221 is 32%, the equivalent refractive index n2 of the second structure 22 is 1.26, and the surface reflectivity of the second structure 22 can be reduced to below 0.1%. At this time, the thickness of the first structure 21 is approximately 380 nm, which encapsulates the optical element 10, acting as a barrier against water and oxygen, thereby preventing failure caused by water absorption in the lens structure 100, the transflective coating 200, the linear polarizing film 500, and the adhesive layer in the optical element 10.

[0092] Figure 3 This is a cross-sectional schematic diagram of an optical structure provided according to another example of an embodiment of the present disclosure. Figure 3 The lens structure 100 in the optical structure shown is... Figure 1 The lens structure 100 in the optical structure shown is different. Figure 3 The phase retardation film 400, reflective polarizing film 300, and linear polarizing film 500 in the optical structure shown can be combined with... Figure 1 The phase retardation film 400, the reflective polarizing film 300, and the linear polarizing film 500 in the optical structure shown have the same characteristics, which will not be described in detail here. Figure 3 The light-transmitting protective film 20 in the optical structure shown can be with Figure 2 The light-transmitting protective film 20 shown has the same morphological features, such as including a first structure 21 and a second structure 22 stacked together. The second structure 22 is in contact with air, and the first structure 21 is in contact with the optical element 10. The density of the first structure 21 is greater than that of the second structure 22. The second structure 22 includes a plurality of microstructures 221. At least some of the microstructures 221 have a characteristic dimension in the direction parallel to the surface of the first structure 21 in contact with the optical element 10. The characteristic dimension is not greater than the operating wavelength of the optical element 10. More detailed features of the light-transmitting protective film will not be described here.

[0093] For example, such as Figure 3 As shown, the lens structure 100 includes a lens 104 and a lens 105. The lens surface of lens 104 facing lens 105 and the lens surface of lens 105 facing lens 104 are both planar. The surfaces of lens 104 and lens 105 away from lens 105 are both convex. For example, an air gap is provided between lens 104 and lens 105. For example, the plane of lens 105 near lens 104 uses an OCA-bonded linear polarizing film 500 and a reflective polarizing film 300, the plane of lens 104 near lens 105 uses an OCA-bonded phase retardation film 400, and the surface of lens 104 away from lens 105 is coated with a reflective coating 200.

[0094] For example, such as Figure 3 As shown, the lens surface of lens 104 away from lens 105 is the first lens surface 111, the lens surface of lens 105 away from lens 104 is the second lens surface 112, the surface of the transflective film 200 away from lens 105 is the first surface 11 of optical element 10, and the second lens surface 112 is the second surface 12 of optical element 10.

[0095] For example, such as Figure 3 As shown, both lens 104 and lens 105 are formed using plasma chemical vapor deposition (PECVD) with HMDSO as a precursor. A dense amorphous silicon coating with alkyl groups is formed on the entire surface of lens 104 and lens 105, which are provided with a transflective coating 200, a phase retardation coating 400, a reflective polarizing coating 300 and a linear polarizing coating 500. The thickness of the coating is 250 nanometers. Then, ICP plasma etching is used with a mixed gas of Ar, O2 and CF6 to etch a portion of the silicon coating surface to a depth of about 90 nanometers to form a second structure 22 with microstructure 221. The effective refractive index of the second structure 22 changes continuously, gradually decreasing from the direction away from the air to the direction closer to the air, so that the surface reflectivity is less than 0.05%.

[0096] Figure 3 The light-transmitting protective film 20 shown not only protects the polymer with high water absorption rate and isolates water vapor, but also covers the convex surface of the lens 105, which improves abrasion resistance, dirt resistance and reduces reflection. On the reflective polarizing film 300 on the plane of the lens 105, the reflectivity of light transmitted through the transmission axis of the reflective polarizing film 300 can be reduced, thereby improving image contrast. The plane of the lens 104 can reduce reflection and suppress ghosting. The convex surface of the lens 104 can protect the oxide material in the transflective film 200 from moisture absorption, and its optical properties can be maintained through film system adjustment.

[0097] The light-transmitting protective film covering the surface of optical elements provided in this disclosure not only overcomes the shortcomings of general high-performance waterproof coatings, such as Parylene, which affect the reflectivity and transmittance of optical elements due to their thickness.

[0098] Of course, the lens structure 100 in the optical structure provided in this disclosure is not limited to including Figure 3 The two lenses shown or Figure 1 The three lenses shown may also include one lens, four lenses, or more lenses; the positional relationship between the transflective coating 200, the phase retardation coating 400, the reflective polarizing coating 300, and the phase retardation coating 400 and the lens structure 100 can be set as needed.

[0099] Figure 4This is a partial cross-sectional structural schematic diagram of a display device provided according to another embodiment of the present disclosure.

[0100] like Figure 4 As shown, the display device includes a display screen 30 and the optical structure provided in any of the above embodiments. Figure 4 The optical structure is shown schematically as follows: Figure 1 The optical structure shown is not limited to this; it can also be... Figure 3 The optical structure shown.

[0101] like Figure 4 As shown, the optical structure is located on the display side of the display screen 30, and the second surface 12 of the optical element 10 is located on the side of the first surface 11 away from the display screen 30.

[0102] For example, such as Figure 4 As shown, the display surface of the display screen 30 is located on the focal plane of the light-incident side of the optical structure.

[0103] For example, such as Figure 4 As shown, the display screen 30 can be any type of display screen 30, such as liquid crystal display screen 30, inorganic light-emitting diode display screen 30, quantum dot display screen 30, projector (such as LCOS micro projector), etc.

[0104] For example, such as Figure 4 As shown, the display screen 30 can be a silicon-based organic light-emitting diode display screen with extremely high pixel density. The optical structure has high definition and a large field of view. The diffusion spot of the optical structure in the center field of view is smaller than the size of a sub-pixel (micrometer level), and the full field of view can exceed 100 degrees.

[0105] For example, the display device can be a virtual reality (VR) display device. For example, a virtual reality display device can be a display device that employs an ultra-short-throw folded optical path.

[0106] For example, the display device can be a near-eye display device, such as a wearable VR helmet or VR glasses, but the embodiments disclosed herein are not limited thereto.

[0107] The following points need to be explained:

[0108] (1) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure, and other structures can be referred to the general design.

[0109] (2) Where there is no conflict, features of the same embodiment and different embodiments of this disclosure may be combined with each other.

[0110] The above description is merely an exemplary embodiment of this disclosure and is not intended to limit the scope of protection of this disclosure, which is determined by the appended claims.

Claims

1. An optical structure comprising: An optical element includes a first surface and a second surface disposed opposite to each other; A light-transmitting protective film is located between the optical element and the air, and the light-transmitting protective film is in contact with at least one of the first surface and the second surface. The optical element includes a lens structure and a transflective coating, a reflective polarizing coating, and a phase retardation coating disposed on the lens structure. The lens structure includes a first lens surface and a second lens surface located on its light-incident side and light-out side, respectively. At least one of the first lens surface and the second lens surface is a curved surface. The reflective polarizing coating and the phase retardation coating are both located on the side of the transflective coating facing the second lens surface. The first surface and the second surface include at least one of the surface of the transflective coating, the surface of the phase retardation coating, the surface of the reflective polarizing coating, the first lens surface, and the second lens surface. The light-transmitting protective film includes a first structure and a second structure stacked together. The second structure is in contact with the air, and the first structure is in contact with the optical element. The density of the first structure is greater than that of the second structure. The second structure includes a plurality of microstructures. At least some of the microstructures have a characteristic dimension in the pitch of the microstructures in the direction parallel to the surface of the first structure in contact with the optical element. The characteristic dimension is not greater than the operating wavelength of the optical element. The first structure and the second structure are integrally formed. The water vapor permeability coefficient of the material of the first structure is ≤1 g·mm / (m). 2 •24h).

2. The optical structure according to claim 1, wherein, The feature size is 10~300 nanometers.

3. The optical structure according to claim 1, wherein, The average thickness of the light-transmitting protective film is 50 nanometers to 10 micrometers.

4. The optical structure according to claim 1, wherein, The average thickness of the second structure is 20-300 nanometers.

5. The optical structure according to claim 1, wherein, The refractive index of the first structure is greater than the equivalent refractive index of the second structure. The refractive index of the first structure is 1.4 to 2.

5. Along the alignment direction from the first structure to the second structure, the equivalent refractive index of the second structure gradually decreases.

6. The optical structure according to claim 5, wherein, Each microstructure has a cross-sectional dimension in a direction parallel to the surface of the first structure that contacts the optical element, and the cross-sectional dimension of at least some of the microstructures gradually decreases along the arrangement direction.

7. The optical structure according to claim 6, wherein, The shape of at least some of the microstructures includes a frustum or a cone.

8. The optical structure according to any one of claims 1-7, wherein, The material of the light-transmitting protective film includes one or more of the following: parylene and its various substituted derivatives, hexamethyldisiloxane, polytetrafluoroethylene, acrylic acid, and fluorosilane.

9. The optical structure according to any one of claims 1-7, wherein, The second structure in the light-transmitting protective film is configured to have a reflectivity of less than 0.2% for visible light.

10. The optical structure according to any one of claims 1-7, wherein, The light-transmitting protective film completely surrounds the optical element.

11. The optical structure according to any one of claims 1-7, further comprising: A linear polarizing film is located on the side of the reflective polarizing film away from the transmissive film.

12. The optical structure according to claim 11, wherein, The second surface includes the linearly polarizing film.

13. A display device, comprising a display screen and the optical structure according to any one of claims 1-12, in, The optical structure is located on the display side of the display screen, and the second surface is located on the side of the first surface away from the display screen.

14. A method for fabricating the optical structure according to any one of claims 1-12, comprising: The plurality of microstructures in the light-transmitting protective film are formed using plasma etching.

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