Optical coating, manufacturing method of optical coating and projection screen

Abstract

The invention discloses an optical coating, a manufacturing method of the optical coating and a projection screen, relates to the technical field of projection display, and aims at solving the problem that speckles of an existing projection screen are relatively serious. The optical coating is used for manufacturing a film layer for forming a projection screen, and the optical coating comprises a water-based organic resin emulsion, deionized water and a matting material. The aqueous organic resin emulsion is used to form a base solution for optical coatings. The deionized water is mixed with the water-based organic resin emulsion. The extinction material is mixed in the water-based organic resin emulsion and the deionized water. The extinction material is used for scattering the light passing through the extinction material. The optical coating is used for improving the quality of a projection picture.

Description

Technical Field

[0001] The present application relates to the technical field of projection display, and in particular, to an optical coating, a manufacturing method of the optical coating, and a projection screen. Background Art

[0002] With the continuous development of technology, projection technology is increasingly applied to people's work and life. Projection technology mainly divides light into three colors: red, green, and blue, then generates images of various colors, synthesizes the three-color images into one image through various optical elements, and finally projects the image.

[0003] In the technical field of projection display, a projector is generally used in combination with a projection screen. The light emitted by the projector is projected onto the projection screen, and after being reflected by the projection screen, it reaches the eyes of the audience, and the audience can view the image formed by the light on the surface of the projection screen.

[0004] In order to increase the applicable environment of the projection screen, a projection coating can be used to form the film structure of the projection screen to make a high-performance projection screen. However, when the currently used projection screen made of projection coating is in use, obvious speckles often appear, which affects the display effect of the picture. Summary of the Invention

[0005] The present application provides an optical coating, a manufacturing method of the optical coating, and a projection screen, which are used to solve the problem that the existing projection screen has relatively serious speckles.

[0006] To achieve the above object, the present application adopts the following technical solutions:

[0007] On the one hand, an embodiment of the present application provides an optical coating for manufacturing a film layer of a projection screen. The optical coating includes an aqueous organic resin emulsion, deionized water, and a matting material. The aqueous organic resin emulsion is used to form the basic base liquid of the optical coating. The deionized water is mixed with the aqueous organic resin emulsion. The matting material is mixed in the aqueous organic resin emulsion and deionized water. The matting material is used to scatter the light passing through the matting material.

[0008] In the optical coating provided by the embodiment of the present application, both the aqueous organic resin emulsion and the deionized water are materials with relatively high transparency, so that the overall optical coating does not block the propagation of light. When light is incident and exits, it will pass through the optical coating and be scattered by the matting material therein, so that the optical path and scattering angle of the light are changed. Thereby reducing the coherence of the light, thus eliminating the number of speckles and reducing the influence of the speckles on the image displayed on the projection screen. At the same time, the aqueous organic resin emulsion is a green and environmentally friendly coating, which does not contain organic solvents. Therefore, when the aqueous organic resin emulsion volatilizes, the emission of organic compounds is very low, and no substances such as formaldehyde and benzene that will pollute the environment will be generated.

[0009] In some embodiments, the aqueous organic resin emulsion includes an aqueous acrylic emulsion.

[0010] In some embodiments, the optical coating further includes coating aids. The coating aids include at least one of a dispersant, a leveling agent, and an antifoaming agent. The dispersant is used to prevent sedimentation and aggregation of particles in the optical coating. The leveling agent is used to form a smooth coating film during the film-forming process of the optical coating. The antifoaming agent is used to prevent the generation of bubbles in the optical coating.

[0011] In some embodiments, the weight portion of the aqueous organic resin emulsion is 50 to 100 parts. The weight portion of deionized water is 25 to 50 parts. The weight portion of the matting material is 1 to 5 parts. The weight portion of the coating aids is 1 to 5 parts.

[0012] On the other hand, an embodiment of the present application also provides a method for manufacturing an optical coating. The method includes the steps of manufacturing and forming an aqueous organic resin emulsion, adding deionized water to the aqueous organic resin emulsion and stirring for dilution, and adding a matting material to the aqueous organic resin emulsion.

[0013] In some embodiments, manufacturing and forming the aqueous organic resin emulsion includes the steps of mixing deionized water, an emulsifier, and an initiator to form an initiation solution, and adding an aqueous organic resin monomer into the initiation solution. Wherein, the aqueous organic resin monomer forms an aqueous organic resin emulsion after emulsion polymerization in the initiation solution.

[0014] In some embodiments, before adding the aqueous organic resin monomer into the initiation solution, manufacturing and forming the aqueous organic resin emulsion further includes the step of heating the initiation solution to make the temperature of the initiation solution be 50°C to 100°C.

[0015] In some embodiments, after adding the aqueous organic resin monomer into the initiation solution, manufacturing and forming the aqueous organic resin emulsion further includes the step of maintaining the temperature of the initiation solution after adding the aqueous organic resin monomer at 50°C to 100°C for 1 h to 2 h.

[0016] In some embodiments, after maintaining the temperature of the initiation solution after adding the aqueous organic resin monomer at

[0017] 50°C to 100°C for 1 h to 2 h, manufacturing and forming the aqueous organic resin emulsion further includes the step of lowering the temperature of the initiation solution after adding the aqueous organic resin monomer to 20°C to 25°C, adding an alkali solution, and adjusting the pH value of the initiation solution after adding the aqueous organic resin monomer to 7 to 8.

[0018] On the other hand, an embodiment of the present application further provides a projection screen, including a reflective layer and a functional layer. The reflective layer is used for reflecting light. The functional layer is stacked on one side of the reflective layer. The functional layer is made of any one of the above optical coatings.

[0019] The technical effects produced by the projection screen including any one of the above optical coatings are the same as those of the above optical coatings, and will not be elaborated here. Description of the Drawings

[0020] Figure 1 Schematic diagram of the state of reflected light of different projection screens in the prior art;

[0021] Figure 2 Schematic diagram of the structure of a black grid anti-light curtain in the prior art;

[0022] Figure 3 Schematic diagram of the structure of a Fresnel anti-light curtain in the prior art;

[0023] Figure 4 Schematic diagram of the states with and without speckles in the prior art;

[0024] Figure 5 Schematic diagram of the usage state of a speckle-reducing projection screen in the prior art;

[0025] Figure 6 Schematic diagram of the usage state of the projection system provided by the embodiment of the present application;

[0026] Figure 7 One of the schematic diagrams of the usage state of a projection screen provided by the embodiment of the present application;

[0027] Figure 8 Schematic diagram of the structure of a projection screen provided by the embodiment of the present application;

[0028] Figure 9 Another schematic diagram of the usage state of a projection screen provided by the embodiment of the present application;

[0029] Figure 10 Still another schematic diagram of the usage state of a projection screen provided by the embodiment of the present application;

[0030] Figure 11 Schematic diagram of the polymerization process of the waterborne acrylic resin provided by the embodiment of the present application;

[0031] Figure 12 Schematic diagram of the usage state of the light extinction particles provided by the embodiment of the present application;

[0032] Figure 13 Schematic diagram of the process flow of a method for preparing an optical coating provided by the embodiment of the present application;

[0033] Figure 14 One of the flow diagrams of the method for preparing the aqueous organic resin emulsion provided by the embodiment of the present application;

[0034] Figure 15 Two of the flow diagrams of the method for preparing the aqueous organic resin emulsion provided by the embodiment of the present application;

[0035] Figure 16 Three of the flow diagrams of the method for preparing the aqueous organic resin emulsion provided by the embodiment of the present application;

[0036] Figure 17 Four of the flow diagrams of the method for preparing the aqueous organic resin emulsion provided by the embodiment of the present application;

[0037] Figure 18 Four of the schematic diagrams of the usage state of a projection screen provided by the embodiment of the present application;

[0038] Figure 19 Five of the schematic diagrams of the usage state of a projection screen provided by the embodiment of the present application.

[0039] Reference numerals:

[0040] 010 - Reflective layer; 020 - Parallel layer; 030 - Diffusion spot projection screen; 031 - Reflective layer; 032 - Fresnel lens layer; 033 - Functional layer; 0331 - Diffusion particles; 034 - Substrate layer; 100 - Projection system; 10 - Projection screen; 11 - Reflective layer; 12 - Functional layer; 20 - Projector; 30 - Audience; 40 - Optical coating; 41 - Extinction particles. Detailed embodiments

[0041] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0042] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "inner", "outer", "center", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0043] Hereinafter, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0044] In the description of the present application, unless otherwise specified, " / " means "or". For example, A / B may mean A or B. "And / or" herein is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, "at least one" means one or more, and "a plurality" means two or more.

[0045] In the embodiments of the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising such element.

[0046] In the embodiments of the present application, words such as "exemplary" or "for example" are used to mean for example, illustration or explanation. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0047] The technology of projection display has now been perfectly integrated into our lives, and the application of projection can be seen in daily entertainment.

[0048] The projection display technology consists of several key components such as a light source, optical elements, a control circuit, and a projection screen. Among them, the light source is responsible for generating light beams. The optical elements can focus, deflect, and split the light beams to project the image onto the screen. The control circuit controls the working states and parameters of each component according to the input signal to achieve the generation and display of the image.

[0049] The projection screen is one of the essential accessories for projection display. For a good projection display device to obtain a good projection effect, a good projection screen is needed to match it. The picture that the viewer watches is directly presented through the projection screen, so the projection screen and the projection display device are complementary to each other.

[0050] As Figure 1 shown Figure 1 is a schematic diagram of the state of the reflected light of different projection screens in the prior art. The principle of a projection screen is that light is projected onto a curtain, and there is usually a layer of coating on the curtain. This coating reflects light, and this reflection process can be divided into two types: diffuse reflection and specular reflection. Diffuse reflection is caused by the uneven surface of the reflecting surface, which makes the light reflect in all directions, resulting in problems such as light not being concentrated and low light brightness. However, because diffuse reflection reflects light in all directions, the range of light reflection in diffuse reflection is relatively wide, enabling viewers to have a larger viewing angle of the image on the projection screen. Specifically, paper and walls can cause diffuse reflection of light.

[0051] The principle of specular reflection is opposite to that of diffuse reflection. The light reflected through specular reflection has a definite reflection direction. Specifically, a mirror can cause specular reflection of light.

[0052] Therefore, under the condition that the projection image and the surrounding environment remain unchanged, the factor affecting the brightness and maximum viewing angle of the projection image is the reflecting surface during the light reflection process, that is, the side of the curtain with the coating.

[0053] In a projection display system, viewers specifically obtain images by receiving the light diffusely reflected from the projection screen. Therefore, the projection screen has a great impact on the image quality displayed by the projection display system. Through reasonable design and selection of the projection screen, higher image quality can be obtained within a suitable angle for the projection image.

[0054] Since the projection system has various application scenarios and different scenarios have different parameter requirements for the projection screen, the projection screen has many classifications. According to the projection display method, projection screens can be divided into D-type diffuse reflection screens, B-type incident angle gain reflection screens, S-type reflection angle upper gain reflection screens, and R-type projection screens, etc.

[0055] At the same time, projection screens can be divided into white plastic screens, metal screens, gray fiberglass screens, and glass bead screens, etc. according to the material of the coating on the surface. These projection screens are covered with various particle coatings or optical coatings on the surface. The curtain in a white plastic screen is woven from textile threads, and the surface of the curtain is coated with PVC material with a special projection effect. However, the white plastic screen will cause diffuse reflection of light from all directions. Therefore, when the stray light in the environment is very strong, it is easy to cause a decrease in the contrast of the image, resulting in a blurred image.

[0056] The curtain of a gray fiberglass screen is made of gray wood, the surface of the curtain is coated with glass fiber, and special optical patterns are engraved on the surface of the projection area.

[0057] The screen of the glass bead screen is woven from textile threads, and a layer of very fine glass beads is sprayed on the surface of the screen, and the glass beads have a strong reflectivity. However, the viewing angle of the glass bead screen is relatively small.

[0058] The metal screen is made by forming the screen into a fine curved surface shape and then coating the screen with silver aluminum powder. However, the side of the metal screen coated with aluminum powder will cause specular reflection of light, making it easy to produce bright spots on the screen and affecting the viewing effect of the picture.

[0059] In addition to the above several types of screens on the projection screen, there is also an anti-light screen that can be used in a bright environment in cooperation with the projection product. This type of anti-light screen can be divided into a black grid anti-light screen and a Fresnel anti-light screen according to the surface microstructure.

[0060] As Figure 2 shown, Figure 2 is a schematic structural diagram of a black grid anti-light screen in the prior art. The black grid anti-light screen is made into a series of parallel prisms with a special process, and has a special optical microstructure with a sawtooth-shaped cross-section. The prisms are black and white. The white inclined surface of the prism is the reflective layer 010. The projection light is projected from the bottom up onto the white reflective layer 010 and then reflected into our eyes, while the interfering light from above will be absorbed by the black parallel layer 020.

[0061] As Figure 3 shown, Figure 3 is a schematic structural diagram of a Fresnel anti-light screen in the prior art. The anti-light screen can also use a Fresnel anti-light screen. The surface structure of the Fresnel anti-light screen is concentric circular prism patterns from large to small, which can simultaneously block the ambient stray light from above and from the left and right sides of the screen.

[0062] Whether it is Fresnel or black grid, essentially, they both belong to physical structural anti-light screens. Corresponding to this is the anti-light screen with an optical coating. This type of screen achieves the anti-light effect by using a special optical coating to absorb and reflect light of a specific wavelength.

[0063] Therefore, it can be understood that in order to cope with different usage environments, we need to select the most suitable one from the above different types and different characteristics of projection screens. In addition, in laser projection, we also need to consider the influence of the projection screen on laser speckle. Even for the same laser display projection device, the speckle performance of different projection screens will vary significantly, because the surface roughness, gloss, and color of the projection screen are all related to the size of the speckle on the picture.

[0064] Among them, laser projection display technology is the fourth-generation display technology following black-and-white display, color display, and digital display. It uses red, green, and blue lasers as display light sources, can reproduce the rich and colorful colors of the objective world most realistically, provide more shocking expressiveness, and has broad market prospects due to its characteristics of high brightness, wide color gamut, high contrast ratio, and low energy consumption. It is the future development trend of display technology.

[0065] As Figure 4 shown, Figure 4 Figure 1 shows the schematic diagrams of the states with and without speckles in the prior art. The surface of the projection screen can be regarded as being composed of a large number of surface elements with irregular distributions, and the laser itself has high temporal coherence and spatial coherence. When the laser emitted by the projector irradiates the projection screen, different surface elements will cause different optical path differences in the reflection or scattering of the incident coherent light, and the reflected or scattered light waves will interfere with each other when they meet in space. The interference of light will produce bright spots and dark spots, which are speckles. The speckles will present a randomly distributed granular pattern on the projection screen, which will seriously affect the quality of the image and information projected on the projection screen.

[0066] The speckle problem of laser projection products is related not only to the host but also to the projection display screen. Different physical properties of the projection screen, such as different substrates, processing methods, materials, surface topographies, colors, and glossiness, will affect the size of the displayed speckles. Because laser speckles are caused by its own high temporal coherence and spatial coherence, when the laser irradiates the surface of the projection screen, these different characteristics of the projection screen will add different phases to the incident light, change the coherence of the laser, and then affect the size of the speckles. Therefore, in projection display, it is hoped to find a projection screen with high picture quality and low speckle contrast ratio to obtain the best display effect.

[0067] How to suppress speckles has always been a key concern in the field of laser display. One solution is to suppress speckles by improving the screen hardware. However, common white plastic screens, metal screens, gray fiberglass screens, and glass bead screens do not have an additional function of dissipating speckles.

[0068] Vibrating the screen is a commonly used speckle suppression scheme. The vibration of the screen causes multiple spatially incoherent speckle patterns at the same position of the picture, resulting in the intensity superposition on the speckles, and uses the compensation effect of the human eye on dynamic images to reduce the speckle contrast ratio, thereby reducing the impact of speckles on the image.

[0069] However, the structure of the vibrating screen in this scheme is complex, and the clarity of the picture will become worse after the screen vibrates. There are also inevitable problems such as poor reliability and high noise.

[0070] Currently, in the industry, there are also solutions to suppress speckle through a multi-layer optical functional layer structure. For example, a matte layer, a light-transmitting layer, and a diffusion layer are laminated together to achieve the purpose of suppressing speckle. However, in this solution, the layer structure is complex. When light penetrates the functional layer, the optical path is long, which will seriously affect the picture quality and clarity.

[0071] As Figure 5 shown, Figure 5 FIG. 1 is a schematic diagram of the usage state of a speckle-reducing projection screen in the prior art. Currently, in order to reduce the influence of speckle commercially, the commonly used speckle-reducing projection screen 030 is composed of a variety of laminated optical structure layers, including a reflective layer 031, a Fresnel lens layer 032, and a functional layer 033.

[0072] The functional layer 033 may include a diffusion and light homogenization layer, a color layer, a viewing angle adjustment layer, an anti-glare layer, an anti-scratch layer (not shown in the figure), etc.

[0073] As Figure 5 shown, diffusion particles 0331 may be provided in the diffusion and light homogenization layer. The material of the diffusion particles 0331 may be PMMA (Polymethyl Methacrylate). The diffusion particles 0331 enable the functional layer 033 to have the effect of eliminating some speckles.

[0074] When the speckle-reducing projection screen 030 is in use, the incident light irradiates the speckle-reducing projection screen 030 and enters the speckle-reducing projection screen 030. Then, it is reflected by the reflective layer 031 at the reflective surface of the Fresnel lens layer 032 and finally exits the speckle-reducing projection screen 030.

[0075] In this speckle-reducing projection screen 030, the diffusion particles 0331 are provided in the functional layer 033, and a substrate layer 034 is further provided between the functional layer 033 and the Fresnel lens layer 032. Therefore, after the light is diffused in the functional layer 033, it has to pass through the substrate layer 034 before reaching the Fresnel lens layer 032. Therefore, the propagation path of the diffused light before reaching the Fresnel lens layer 032 is long, and the coherence of the light at the Fresnel lens layer 032 is greatly reduced, so that some speckles can be eliminated to a certain extent.

[0076] Although this speckle-reducing projection screen 030 can eliminate some speckles, its structure is relatively complex and it cannot be applied to a variety of laser display usage environments, and the speckle elimination effect is relatively not obvious.

[0077] Projection paint, as a kind of coating, is made by adding optical reflective materials into latex paint. It can be painted to make a high-performance projection screen. It does not require special tools and skills, is not restricted by size and usage scenarios, and has very good convenience.

[0078] However, the existing projection coatings on the market do not have a special speckle dissipation function. Therefore, in the cooperation with laser projection, obvious speckle phenomena often occur, which will affect the picture quality.

[0079] Based on this, the embodiment of the present application provides a projection system, which is used for the audience to project and play pictures, videos, etc.

[0080] As Figure 6 shown, Figure 6 is a schematic diagram of the usage state of the projection system 100 provided by the embodiment of the present application. The projection system 100 includes a projection screen 10 and a projector 20. For the convenience of describing the projection system 100, the present application takes the state when the projection screen 10 is unfolded in a certain vertical plane as an example for description, and defines the direction in which the audience 30 looks at the small projection screen 10 as the front view direction.

[0081] In use, the projector 20 can be placed in the front lower part of the projection screen 10, and the audience 30 is located in front of the projection screen 10 and looks at the projection screen 10. The incident light emitted by the projector 20 shines on the projection screen 10, and the incident light is finally reflected by the projection screen 10 to form an outgoing light that shines on the audience 30, and at the same time, an image is formed on the projection screen 10.

[0082] Exemplarily, the projection display technology of the above projector 20 can be DLP projection technology, 3LCD projection technology, LCD projection technology, LCOS projection technology, ALPD projector technology. No matter which type of projection display technology, the light is first divided into three colors of red, green and blue, and various color images are generated. The three-color images are combined into one image through various optical elements, and then projected onto the screen through a lens.

[0083] Exemplarily, Figure 6 the projector 20 shown can include a laser, and the laser can be one of a single-color laser, a two-color laser and a three-color laser. Among them, the three-color laser can emit blue laser, red laser and green laser.

[0084] The wavelength range of the blue laser emitted by the laser can be set to 430nm - 460nm, the wavelength range of the green laser emitted can be set to 500nm - 540nm, and the wavelength range of the red laser emitted can be set to 610nm - 650nm. Of course, the projector 20 can also be a projector 20 that emits ordinary light.

[0085] In some embodiments, as Figure 7 shown, Figure 7 is one of the schematic diagrams of the usage state of a projection screen 10 provided by the embodiment of the present application. The projection screen 10 can include a reflective layer 11 and a functional layer 12.

[0086] The reflective layer 11 is used to reflect light. The functional layer 12 is stacked on one side of the reflective layer 11. The functional layer 12 is made of an optical coating 40.

[0087] Along the stacking direction of the functional layer 12 and the reflective layer 11, the projector 20 is located on the side of the functional layer 12 away from the reflective layer 11, and the audience 30 is located on the side of the functional layer 12 close to the projector 20.

[0088] In this way, after the light projected by the projector 20 reaches the reflective layer 11, it will be reflected by the reflective layer 11 to the side where the projector 20 is located and enter the eyes of the audience 30, and the audience 30 can view the image on the projection screen 10.

[0089] In some embodiments, as Figure 8 shown, Figure 8 is a schematic structural diagram of a projection screen 10 provided by an embodiment of the present application. The optical coating 40 that makes up the functional layer 12 is used to form the film layer of the projection screen 10. The optical coating 40 may include an aqueous organic resin emulsion, deionized water, and a light extinction material.

[0090] The aqueous organic resin emulsion is used to form the basic base liquid of the optical coating 40. The deionized water is mixed with the aqueous organic resin emulsion. The light extinction material is mixed in the aqueous organic resin emulsion and deionized water. The light extinction material is used to scatter the light passing through it.

[0091] When the projection screen 10 is in use, the incident light emitted by the projector 20 shines on the projection screen 10. The incident light first passes through the optical coating 40, and most of the light will be randomly scattered and refracted by the light extinction material in the optical coating 40. Through these scattering and refraction, the propagation path of the light will be increased, reducing the coherence of the light at the optical coating 40, thereby eliminating speckles to a certain extent.

[0092] At the same time, as Figure 9 and Figure 10 shown, Figure 9 is a second schematic diagram of the use state of a projection screen 10 provided by an embodiment of the present application, Figure 10 is a third schematic diagram of the use state of a projection screen 10 provided by an embodiment of the present application. After the light enters the optical coating 40 and is scattered and refracted by the light extinction material, the light extinction material will randomly change the phase difference, amplitude, and propagation angle of the light.

[0093] After that, the light will be reflected at the reflective layer 11. The reflected light will pass through the optical coating 40 again, be scattered and refracted by the light extinction material, and then exit the projection screen 10. Finally, the scattering angle of the exiting light will be larger than that of the incident light. Increasing the scattering angle of the light can also reduce the coherence of the light and eliminate speckles to a certain extent.

[0094] The optical coating 40 provided by the embodiments of the present application, wherein both the waterborne organic resin emulsion and deionized water are materials with relatively high transparency, so that the overall optical coating 40 will not block the propagation of light. When light is incident and exits, it will pass through the optical coating 40 and be scattered by the light extinction material therein, so that the optical path and scattering angle of the light are changed. Thereby reducing the coherence of the light, eliminating the number of speckles, and reducing the influence of the speckles on the image displayed on the projection screen 10.

[0095] The waterborne organic resin emulsion is a green and environmentally friendly coating. It does not contain organic solvents. Therefore, when the waterborne organic resin emulsion volatilizes, the emissions of organic compounds are very low, and no substances such as formaldehyde and benzene that will pollute the environment will be generated. At the same time, the waterborne resin emulsion does not contain harmful substances and will not cause damage to human health.

[0096] Deionized water can be mixed with the waterborne organic resin emulsion to adjust the viscosity of the optical coating 40, so that the optical coating 40 can be more firmly located on the reflective layer 11. At the same time, deionized water has no ions and microorganisms, has high stability, and will not react with the substances in the optical coating 40, affecting the stability of the optical coating 40.

[0097] In some embodiments, the waterborne organic resin emulsion may include a waterborne acrylic emulsion. The polymer structure of the waterborne acrylic emulsion helps the flow and wettability of the molecular chain on the surface of the reflective layer 11, so that the coating is in close contact with the reflective layer 11, achieving high adhesion.

[0098] At the same time, the waterborne acrylic emulsion has good compatibility with various waterborne color pastes, so that the waterborne acrylic emulsion can be well mixed with other materials. And the waterborne acrylic emulsion has relatively high transparency and will not affect the transmission of light, allowing light to pass through the waterborne acrylic emulsion more easily.

[0099] Exemplarily, as Figure 11 shown, Figure 11 is a schematic diagram of the polymerization process of the waterborne acrylic resin provided by the embodiments of the present application. The waterborne acrylic emulsion can be an acrylic resin with hydrophilic functional groups such as hydroxyl, aldehyde, carboxyl, amino, and sulfonic acid groups. Among them, the hydrophilic functional groups can make the waterborne acrylic emulsion better mixed with other materials.

[0100] Of course, the waterborne organic resin emulsion may also include other types of resin emulsions, as long as it can allow light to pass through the waterborne organic resin emulsion.

[0101] In some embodiments, the optical coating 40 may further include coating additives. The coating additives include at least one of a dispersant, a leveling agent, and an antifoaming agent. The dispersant is used to prevent sedimentation and aggregation of particles in the optical coating 40. The leveling agent is used to form a smooth coating film during the film-forming process of the optical coating 40. The antifoaming agent is used to prevent the generation of bubbles in the optical coating 40.

[0102] The dispersant can effectively prevent particles and powders from precipitating or aggregating in a liquid by increasing the surface activity of the particles or powders. At the same time, the dispersant can evenly disperse the particles or powders in the liquid, thereby forming a stable emulsion. Exemplarily, the dispersant can be a polycarboxylate dispersant.

[0103] The leveling agent can effectively reduce the surface tension of the optical coating 40, improve the leveling property and uniformity of the optical coating 40. The leveling agent can also promote the formation of a smooth, glossy and uniform coating film during the drying and film-forming process of the optical coating 40.

[0104] Exemplarily, the leveling agent can be the aqueous leveling agent BYK-333. The aqueous leveling agent BYK-333 has excellent substrate lubrication and leveling properties, good water solubility, low surface tension and anti-cratering function. And the aqueous leveling agent BYK-333 is a polyether-modified silicone, which is safe and environmentally friendly and has no pollution to the environment.

[0105] The antifoaming agent can inhibit and eliminate foam, preventing the foam in the optical coating 40 from reducing the transparency of the optical coating 40, thereby blocking the transmission of light and causing light loss. Exemplarily, the antifoaming agent can be a higher alcohol, a silicone antifoaming agent, or a polyether antifoaming agent.

[0106] In some embodiments, the weight portion of the aqueous organic resin emulsion can be 50 parts to 100 parts. The weight portion of deionized water can be 25 parts to 50 parts. The weight portion of the matting material can be 1 part to 5 parts. The weight portion of the coating additives can be 1 part to 5 parts. Among them, when the above components are within the above ratio ranges, the weight portions of the components can cooperate synergistically, so that the optical coating has a better effect of improving speckle. Of course, the specific ratio of the aqueous organic resin emulsion can also be other ratios, as long as the finally formulated optical coating 40 can have the effect of improving speckle.

[0107] It is understandable that the specific composition of the above different components can be adjusted according to the actual situation. As mentioned above, the weight portion of the aqueous organic resin emulsion is 50 parts to 100 parts. By way of example, the weight portion of the aqueous organic resin emulsion can be 50 parts, 60 parts, 65 parts or 100 parts, etc. The weight portion of deionized water can be 25 parts to 50 parts. Exemplarily, the weight portion of deionized water can be 25 parts, 30 parts, 35 parts or 50 parts, etc. The weight portion of the matting material can be 1 part to 5 parts. Exemplarily, the weight portion of the matting material can be 1 part, 2 parts, 4 parts or 5 parts, etc. The weight portion of the coating auxiliary can be 1 part to 5 parts. Exemplarily, the weight portion of the coating auxiliary can be 1 part, 2 parts, 4 parts or 5 parts, etc.

[0108] Exemplarily, the weight portion of the dispersant in the coating auxiliary can be 1 part to 2 parts, the weight portion of the leveling agent can be 1 part, and the weight portion of the defoamer can be 1 part to 2 parts.

[0109] As Figure 12 shown, Figure 12 is a diagram showing the usage state of the matting particles 41 provided in the embodiment of the present application. The matting material can be matting powder, and the matting powder is composed of many matting particles 41. The matting particles 41 can scatter and refract the light passing through them, thereby changing the optical path and scattering angle of the light, and thus reducing the formation of speckles. The dispersant can make the matting particles 41 evenly distributed in the oily acrylic emulsion, so that the matting particles 41 act on the light everywhere.

[0110] Exemplarily, the speckle contrast can be used to quantify the strength of the speckles. The speckle contrast C S is calculated as follows:

[0111]

[0112] where, is the average intensity of n speckle patterns. When the light intensities of the individual speckles are approximately equal, the formula can be simplified to:

[0113]

[0114] It can be seen from this that as the number N of independent speckles increases, some of the speckles will overlap and cancel each other out, making the speckle contrast C S decrease.

[0115] When light passes through the optical coating 40, it will be multiply refracted and scattered by a large number of matting particles 41 dispersed in the optical coating 40, enhancing the possibility of interference between each light wave, increasing the number of speckles, thereby reducing the speckle contrast and reducing the influence of the speckles on the picture quality presented on the projection screen 10.

[0116] Exemplarily, speckle reduction can be achieved by reducing the spatial coherence of the incident light. According to the Cittert–Zernike law, the expression formula for the spatial average coherence width of light is as follows:

[0117]

[0118] where ΔS is the spatial average coherence width, λ is the wavelength of the incident light, and θ is the light scattering angle.

[0119] As can be seen from the above formula, as the scattering angle of the light by the extinction particles 41 increases, the spatial average coherence width of the light will decrease accordingly. Thus, the spatial coherence of the light will be reduced, making it difficult for the light to interfere and diffract, and difficult to generate speckles. At the same time, the increase in the scattering angle can also improve the viewing angle of the projection screen 10.

[0120] The scattering angle of the light by the extinction particles 41 is related to the radius of the extinction particles 41.

[0121] Exemplarily, the diameter of the extinction particles 41 can be 500 nm to 20 μm.

[0122] Exemplarily, by controlling the size of the radius of the extinction particles 41, the light scattering ability of the optical coating 40 can be controlled. The expression formula for the degree of light scattering α can be:

[0123]

[0124] where r is the radius of the extinction particles 41 and λ is the wavelength of the incident light. At the same time, when α is much less than 0.1, Rayleigh scattering theory can be used. When α is greater than or equal to 0.1, Mie scattering theory can be used. When α is greater than 50, geometric optics theory can be used.

[0125] According to the above theory, when the radius of the extinction particles 41 is less than the wavelength of the incident light, as the radius of the extinction particles 41 increases, the light scattering ability of the extinction particles 41 increases accordingly. When the radius of the extinction particles 41 is equal to the wavelength of the incident light, the light scattering ability of the extinction particles 41 reaches the strongest. When the radius of the extinction particles 41 is greater than the wavelength of the incident light, as the radius of the extinction particles 41 increases, the light scattering ability of the extinction particles 41 decreases and tends to a fixed value. When the radius of the extinction particles 41 is much greater than the wavelength of the incident light, the scattering ability of the extinction particles 41 is independent of the radius of the extinction particles 41.

[0126] Among them, the radius of the extinction particles 41 should not be too large. When the radius of the extinction particles 41 is relatively large, the surface roughness of the functional layer 12 is relatively large, which will additionally interfere with the scattered light. Thus, the light passing through the functional layer 12 cannot be effectively diffused, ultimately reducing the diffusion effect of the projection screen 10.

[0127] Thus, the speckle contrast results of the light extinction particles 41 with the same and different diameters under different weight fractions can be counted and listed one by one on the same projection system 100, and the above conclusion can be verified. The results are shown in Table 1 below:

[0128] Table 1

[0129] Matting powder / parts by weight Matting powder particle diameter Speckle contrast 0 / 18.7％ 1 500 nm 17.5％ 3 500 nm 14.1％ 5 500 nm 12.5％ 1 10 μm 18.0％ 3 10 μm 16.2％

[0130] Exemplarily, the thickness of the functional layer 12 can be 30 μm to 100 μm. The thickness of the functional layer 12 can ensure that enough light extinction particles 41 can be accommodated therein. It can also protect the reflective layer 11 to a certain extent.

[0131] Exemplarily, the surface roughness Ra of the surface of the functional layer 12 away from the reflective layer 11 can be 1 μm to 5 μm.

[0132] Different roughnesses on the surface of the projection screen 10 will bring different phase differences to the light. The expression formula of the phase difference of the light is as follows:

[0133]

[0134] where σ Φ is the phase difference of the light, and σ h is the fluctuation of the surface height, which is related to the surface roughness.

[0135] By adjusting the roughness of the surface of the projection screen 10 to make the phase difference of the light within a suitable numerical range, the influence of the speckle on the image on the projection screen 10 can be further reduced. At the same time, the appropriate surface roughness can also increase the intensity of the light, thereby relatively reducing the speckle contrast.

[0136] The principles of the above several solutions can all be regarded as introducing a certain number of degrees of freedom. In most cases, if we have N independent mechanisms to introduce new degrees of freedom, then the total number M of degrees of freedom is:

[0137]

[0138] And the obtained speckle contrast is:

[0139]

[0140] On the other hand, as Figure 13 shown, Figure 13 is a schematic flow chart of a method for manufacturing an optical coating 40 provided by an embodiment of the present application. An embodiment of the present application also provides a method for manufacturing an optical coating 40, and the method includes steps S100 to S300.

[0141] S100: Prepare and form an aqueous organic resin emulsion.

[0142] S200: Add deionized water to the aqueous organic resin emulsion and stir for dilution.

[0143] S300: Add a matting material to the aqueous organic resin emulsion.

[0144] An aqueous organic resin emulsion can be prepared first, and then deionized water can be added to adjust the viscosity of the optical coating 40. Finally, a matting material is added.

[0145] In some embodiments, as Figure 14 shown, Figure 14 is one of the flow schematic diagrams of the method for preparing an aqueous organic resin emulsion provided by the embodiment of the present application. Preparing and forming an aqueous organic resin emulsion includes steps S400 to S500.

[0146] S400: Mix deionized water, an emulsifier, and an initiator to form an initiating solution.

[0147] S500: Add an aqueous organic resin monomer to the initiating solution.

[0148] The solution except for the aqueous organic resin monomer can be prepared first, and then the aqueous organic resin monomer can be uniformly dropped into the prepared solution. The aqueous organic resin monomer can be diluted in the prepared solution and then mixed with other substances to form an aqueous organic resin emulsion.

[0149] Among them, the aqueous organic resin monomer will undergo a free radical polymerization reaction in the initiating solution, so that the aqueous organic resin monomer and the initiating solution form an aqueous organic resin emulsion. Moreover, the deionized water in the initiating solution can play a good dilution role, so that the viscosity of the polymerization of the aqueous organic resin monomer and the initiating solution is reduced, making the whole reaction easier to proceed and the reaction more complete, and no gel effect will occur.

[0150] Exemplarily, the emulsifier can be sodium dodecyl sulfate. The initiator can be ammonium persulfate, potassium persulfate, and other persulfates. Among them, the emulsifier can make the system form a relatively stable emulsion. The initiator breaks the chemical bond at high temperature to generate free radicals, thereby initiating the progress of the chemical reaction.

[0151] In some embodiments, as Figure 15 shown, Figure 15 is the second flow schematic diagram of the method for preparing an aqueous organic resin emulsion provided by the embodiment of the present application. Before adding the aqueous organic resin monomer to the initiating solution, preparing and forming an aqueous organic resin emulsion further includes step S600.

[0152] S600: Heat up the initiating solution to keep the temperature of the initiating solution at 50°C - 100°C.

[0153] Thus, after the subsequent aqueous organic resin monomer is added to the initiating solution, a polymerization reaction can occur between the monomer and the initiating solution at a temperature of 50°C - 100°C to obtain an aqueous acrylic resin emulsion with relatively good performance. Because when the reaction system temperature is low, the polymerization reaction is slow and it is difficult to form an aqueous acrylic resin emulsion.

[0154] It should be noted that the temperature of the initiating solution can be less than 100°C. Since the boiling point of water is 100°C, too high a temperature will cause the deionized water to evaporate, resulting in a decrease in the content of deionized water and affecting the polymerization effect between the aqueous organic resin monomer and the initiating solution.

[0155] In some embodiments, as Figure 16 shown, Figure 16 FIG. 3 is a schematic flowchart of the method for preparing an aqueous organic resin emulsion provided by an embodiment of the present application. After adding the aqueous organic resin monomer to the initiating solution, the method for preparing the aqueous organic resin emulsion further includes step S700.

[0156] S700: Keep the initiating solution added with the aqueous organic resin monomer at a temperature of 50°C - 100°C for 1 h - 2 h.

[0157] In this way, the aqueous organic resin monomer and the initiating solution can have sufficient time to carry out the polymerization reaction in a temperature environment suitable for the polymerization reaction, so that the aqueous organic resin monomer can react completely.

[0158] In some embodiments, as Figure 17 shown, Figure 17 FIG. 4 is a schematic flowchart of the method for preparing an aqueous organic resin emulsion provided by an embodiment of the present application. After keeping the initiating solution added with the aqueous organic resin monomer at a temperature of 50°C - 100°C for 1 h - 2 h, the method for preparing the aqueous organic resin emulsion further includes steps S800 - S900.

[0159] S800: Lower the temperature of the initiating solution added with the aqueous organic resin monomer to 20°C - 25°C.

[0160] S900: Add an alkali solution to adjust the pH value of the initiating solution added with the aqueous organic resin monomer to 7 - 8.

[0161] Adjusting the pH value of the initiating solution added with the aqueous organic resin monomer to be weakly alkaline can enhance the overall fluidity of the aqueous acrylic emulsion, so that the aqueous acrylic emulsion can form a relatively flat surface.

[0162] When the temperature of the initiator solution after adding the aqueous organic resin monomer is between 20°C and 25°C, a relatively violent reaction is not likely to occur. Therefore, to ensure the stability and safety of the solution, the temperature of the initiator solution after adding the aqueous organic resin monomer needs to be reduced to 20°C - 25°C before adjusting the pH value.

[0163] After the pH value is adjusted, the emulsion is filtered to remove the incompletely reacted aggregates, and an aqueous acrylic emulsion is obtained.

[0164] Subsequently, based on the viscosity of the currently prepared aqueous acrylic emulsion, it is determined whether deionized water needs to be added and the amount of deionized water to be added, so as to accurately adjust the viscosity of the aqueous acrylic emulsion to an appropriate range.

[0165] Exemplarily, after adjusting the aqueous acrylic emulsion to an appropriate viscosity, a matting material and a dispersant can be added thereto, and then stirred evenly.

[0166] Exemplarily, after adding a matting material and a dispersant to the aqueous acrylic emulsion, an antifoaming agent and a leveling agent can be added thereto, and then stirred evenly.

[0167] When adding the matting material, some air may be brought into the aqueous acrylic emulsion, thereby forming some bubbles in the aqueous acrylic emulsion. Therefore, adding the antifoaming agent after adding the matting particles 41 can remove these bubbles, enabling the aqueous acrylic emulsion to maintain a state of high transparency. The leveling agent can enable the emulsion to form a flat coating film during the film-forming process.

[0168] After completing the above steps, the finished optical coating 40 can be obtained. Then, the optical coating 40 needs to be evenly covered on the surface of the projection screen 10.

[0169] Exemplarily, the method of evenly covering the optical coating 40 on the surface of the projection screen 10 can be brushing, rolling, spraying or other methods. The method is not specifically limited as long as the optical coating 40 can be evenly covered on the surface of the projection screen 10.

[0170] Among them, it should be noted that different methods of evenly covering the optical coating 40 on the surface of the projection screen 10 correspond to different viscosities required for the optical coating 40. Specifically, an appropriate amount of deionized water can be added to the optical coating 40 to adjust the viscosity of the optical coating 40.

[0171] Exemplarily, the type of the projection screen is not specifically limited as long as the side of the projection screen 10 coated with the optical coating 40 can reflect light.

[0172] Thus, as Figure 18 shown, Figure 18This is the fourth schematic diagram of the usage state of a projection screen provided by an embodiment of the present application. When laser light passes through the optical coating, due to the presence of high-transparency waterborne acrylic resin and extinction particles, most of the light passes through the waterborne acrylic resin and is randomly scattered and refracted by the extinction particles therein. Through these scattering and refraction, the phase difference and amplitude of the light are changed. Finally, it is reflected from the surface of the reflection layer 11 and then diffused and refracted back out through the functional layer 12. This entire process can increase the scattering angle of the light output, achieve the superposition of the divergent light beams output by the scattering units, and thereby change the divergence angle and light intensity distribution of the output light beam.

[0173] Meanwhile, as Figure 19 shown, Figure 19 This is the fifth schematic diagram of the usage state of a projection screen provided by an embodiment of the present application. The projection screen 10 of this technical solution only has two layers, namely the functional layer 12 and the reflection layer 11. Compared with the multi-layer structure, the light has a shorter optical path difference when transmitting in the double-layer structure. A shorter optical path difference means a smaller phase difference, which will result in less interference between the lights, thereby being able to reduce the blurring of the image caused by speckle and making the image have a better resolution.

[0174] Exemplarily, for the same laser under different diameters of the extinction particles 41 and different thicknesses of the functional layer 12, the speckle contrast results on the displayed image can be statistically listed one by one, and the results are shown in Table 2 below:

[0175] Table 2

[0176] Matting powder particle diameter Matting film thickness Speckle contrast 500 nm 30 μm 7.9％ 500 nm 50 μm 6.6％ 500 nm 100 μm 6.0％ 1 μm 30 μm 8.7％ 20 μm 30 μm 10.1％

[0177] From this, a further conclusion can be drawn that on the basis of the projection screen 10 with a double-layer structure, when the particle diameters of the extinction particles 41 are the same, the greater the thickness of the functional layer 12, the lower the speckle contrast.

[0178] Meanwhile, as can be seen from Table 2, when the thickness of the extinction film is the same, the smaller the diameter of the extinction powder particles, the lower the speckle contrast.

[0179] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An optical coating for fabricating a film layer forming a projection screen, characterized in that, The optical coating includes: An aqueous organic resin emulsion, which is used to form the base liquid of the optical coating; Deionized water, which is mixed with the aqueous organic resin emulsion; and A matting material, which is mixed in the aqueous organic resin emulsion and the deionized water; the matting material is used to scatter the light passing through it.

2. The optical coating according to claim 1, characterized in that, The aqueous organic resin emulsion includes an aqueous acrylic emulsion.

3. The optical coating according to claim 1, characterized in that, The optical coating further includes: Coating additives, which include at least one of a dispersant, a leveling agent, and an antifoaming agent; the dispersant is used to prevent the sedimentation and aggregation of particles in the optical coating; the leveling agent is used to form a smooth coating film during the film-forming process of the optical coating; the antifoaming agent is used to prevent the generation of bubbles in the optical coating.

4. The optical coating according to claim 3, characterized in that, The weight parts of the aqueous organic resin emulsion are 50 parts to 100 parts; the weight parts of the deionized water are 25 parts to 50 parts; the weight parts of the matting material are 1 part to 5 parts; the weight of the coating additives is 1 part to 5 parts.

5. A method for preparing an optical coating, characterized in that, The manufacturing method includes the steps of: Manufacturing and forming an aqueous organic resin emulsion; Adding deionized water to the aqueous organic resin emulsion and stirring for dilution; Adding a matting material to the aqueous organic resin emulsion.

6. The manufacturing method of the optical coating according to claim 5, characterized in that, Manufacturing and forming an aqueous organic resin emulsion includes the steps of: Mixing deionized water, an emulsifier, and an initiator to form an initiating solution; Adding an aqueous organic resin monomer to the initiating solution; Wherein, the aqueous organic resin monomer forms the aqueous organic resin emulsion after emulsion polymerization in the initiating solution.

7. The manufacturing method of the optical coating according to claim 6, characterized in that, Before adding the aqueous organic resin monomer to the initiating solution, manufacturing and forming the aqueous organic resin emulsion further includes the step of: Raising the temperature of the initiating solution to make the temperature of the initiating solution be 50°C to 100°C.

8. The method for manufacturing an optical coating according to claim 7, characterized in that, After adding the aqueous organic resin monomer to the initiating solution, manufacturing and forming the aqueous organic resin emulsion further includes the step of: Keeping the initiating solution after adding the aqueous organic resin monomer at a temperature of 50°C to 100°C for 1 h to 2 h.

9. The method for manufacturing an optical coating according to claim 8, wherein After keeping the initiating solution after adding the aqueous organic resin monomer at a temperature of 50°C to 100°C for 1 h to 2 h, manufacturing and forming the aqueous organic resin emulsion further includes the steps of: Lowering the temperature of the initiating solution after adding the aqueous organic resin monomer to 20°C to 25°C; Adding an alkali solution to adjust the pH value of the initiating solution after adding the aqueous organic resin monomer to 7 to 8.

10. A projection screen, characterized in that, The projection screen includes: A reflective layer, which is used to reflect light; and A functional layer, which is laminated on one side of the reflective layer; the functional layer is made of the optical coating according to any one of claims 1 to 4.

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