Projection screen, its manufacturing method and projection system

Abstract

This invention discloses a projection screen 1, a manufacturing method, and a projection system. The Zenki projection screen 1 includes a diffusion layer 11, a Fresnel structure layer 12, and a wavelength-selective reflective layer F located on at least a portion of the Fresnel structure 121 of the Fresnel structure layer 12. The wavelength-selective reflective layer F selectively reflects projection light emitted from a projection device 2 while significantly reducing the reflectance of light in other wavelength bands. This allows for a black appearance when the projection device 2 is turned off and a bright display when the projection device 2 is turned on, thereby significantly improving the contrast of the projected image.

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application filed on December 29, 2022 with the Patent Office of the People's Republic of China, bearing application number 202211716475.1, entitled "Projection screen and projection system," the disclosure of which is incorporated herein in its entirety. This application also claims priority from a Chinese patent application filed on December 29, 2022 with the Patent Office of the People's Republic of China, bearing application number 202211716324.6, entitled "Projection screen and projection system," the disclosure of which is incorporated herein in its entirety. This application also claims priority from a Chinese patent application filed on February 10, 2023 with the Patent Office of the People's Republic of China, bearing application number 202310107687.8, entitled "Projection screen, manufacturing method thereof, and projection system," the disclosure of which is incorporated herein in its entirety.

[0002] The present invention relates to the field of projection, and more particularly to a projection screen, a manufacturing method thereof, and a projection system. [Background technology]

[0003] With the spread of laser display products, the market for laser TVs, which are large-screen products that are replacing LCD and organic electroluminescent (EL) TVs, is rapidly expanding. Conventional front projection projection systems are usually used in combination with a projection screen, where the projection light is emitted from the projector, enters the projection screen, and is reflected by the projection screen before entering the human eye, where the projected image is observed. Summary of the Invention [Problem to be solved by the invention]

[0004] White matte projection screens are inexpensive and can reflect light from a light source evenly in all directions. However, white matte projection screens are easily affected by external light when viewed in bright places, making them unsuitable for movies and other images that feature many dark scenes. To solve this problem, some projection screens are colored to absorb ambient light and reduce its brightness. However, because colored projection screens also absorb light emitted from the projection light source, they also reduce the brightness of the projected light, resulting in a reduction in image contrast. [Means for solving the problem]

[0005] A first aspect of an embodiment of the present invention provides a projection screen comprising: a diffusion layer; a Fresnel structure layer located on one side of the diffusion layer and having a Fresnel structure on the surface on that side; and a wavelength-selective reflection layer coated on at least a portion of the surface of the Fresnel structure of the Fresnel structure layer, the wavelength-selective reflection layer having a higher reflectivity for light emitted from a projection device than for light in other wavelength bands.

[0006] A second aspect of the present invention is a manufacturing process of a Fresnel structure, which includes manufacturing a Fresnel structure layer, and having a plurality of Fresnel structures on one side of the Fresnel structure layer, the Fresnel structures having an inclined surface and a connecting surface that are connected to each other; a manufacturing step of a reflective layer, which includes forming a discontinuous first thin film on the inclined surface of the Fresnel structure and forming a continuous second film layer on the first thin film; a surface functional layer manufacturing step of forming a surface functional layer on one side of the Fresnel structure layer with the reflective layer. A method for manufacturing a projection screen is provided.

[0007] A third aspect of the present invention provides a projection device for emitting a projection light beam, comprising: any one of the above projection screens located on the light output side of the projection device, the projection device is an ultra-short focus laser projection device, The projection device is a three-color laser light source device for emitting three primary color laser beams; a light modulation member located on the light output side of the three-color laser light source device, for modulating the laser light output from the three-color laser light source device; a projection lens located on the light output side of the light modulation member. [Brief explanation of the drawings]

[0008] In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings to be used in the embodiments of the present invention are briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without any creative efforts. [Figure 1] 1 is a structural schematic diagram of a projection system according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram of the structure of a projection screen in the related art. [Figure 3] 2 is a schematic diagram of the structure of a projection screen in the related art. [Figure 4] 1 is a schematic structural diagram of a projection screen according to an embodiment of the present invention; [Figure 5] 1 is a schematic structural diagram of a wavelength-selective reflection layer according to an embodiment of the present invention. [Figure 6] FIG. 2 is a schematic structural diagram of a wavelength-selective reflecting layer according to an embodiment of the present invention. [Figure 7] 4 shows reflectance curves of a wavelength selective reflective layer for light rays of different wavelength bands according to an embodiment of the present invention. [Figure 8] 10 is an intensity distribution curve of ambient light according to an embodiment of the present invention. [Figure 9] 1 is a reflectance curve of ambient light incident on a wavelength selective reflection layer according to an embodiment of the present invention. [Figure 10] 10 is a graph showing the relationship between the thickness of a semi-transparent layer and the attenuation rate of ambient light intensity according to an embodiment of the present invention. [Figure 11] 1 is a graph showing a relationship between wavelength and reflectance according to an embodiment of the present invention. [Figure 12] 2 is a curve 2 showing the relationship between wavelength and reflectance according to an embodiment of the present invention. [Figure 13] 3 is a curve 3 showing the relationship between wavelength and reflectance according to an embodiment of the present invention. [Figure 14] 4 is a curve 4 showing the relationship between wavelength and reflectance according to an embodiment of the present invention. [Figure 15] 5 is a curve 5 showing the relationship between wavelength and reflectance according to an embodiment of the present invention. [Figure 16] 6 is a curve 6 showing the relationship between wavelength and reflectance according to an embodiment of the present invention. [Figure 17] 2 is a schematic structural diagram of a projection screen according to an embodiment of the present invention; [Figure 18] FIG. 10 is a comparison diagram of reflectance curves for different angles of incidence according to an embodiment of the present invention. [Figure 19] 3 is a schematic structural diagram of a projection screen according to an embodiment of the present invention; [Figure 20] 1 is a reflectance curve of a light beam having an incident angle of 65° by a wavelength selective reflection layer according to an embodiment of the present invention. [Figure 21] 1 is a reflectance curve of a light beam having an incident angle of 10° by a wavelength selective reflection layer according to an embodiment of the present invention. [Figure 22] 4 is a reflectance curve after two reflections by a wavelength-selective reflective layer according to an embodiment of the present invention. [Figure 23] 4 is a relative intensity curve of ambient light incident on a projection screen according to an embodiment of the present invention. [Figure 24] 4 is a relative intensity curve of ambient light after reflection by a projection screen according to an embodiment of the present invention. [Figure 25] 4 is a schematic structural diagram of a projection screen according to an embodiment of the present invention. [Figure 26] 5 is a schematic structural diagram of a projection screen according to an embodiment of the present invention. [Figure 27] 6 is a schematic structural diagram of a projection screen according to an embodiment of the present invention. [Figure 28] 7 is a schematic structural diagram of a projection screen according to an embodiment of the present invention. [Figure 29]8 is a schematic structural diagram of a projection screen according to an embodiment of the present invention. [Figure 30] 9 is a structural schematic diagram of a projection screen according to an embodiment of the present invention. [Figure 31] 10 is a schematic structural diagram of a projection screen according to an embodiment of the present invention. [Figure 32] 3 is a schematic diagram of the structure of a projection screen in the related art. [Figure 33] 4 is a schematic diagram of the structure of a projection screen in the related art. [Figure 34] FIG. 1 is a flowchart of a method for manufacturing a projection screen according to an embodiment of the present invention. [Figure 35] 1 is a schematic diagram of a manufacturing flow of a Fresnel structure layer according to an embodiment of the present invention. [Figure 36] 2 is a schematic diagram of a manufacturing flow of a Fresnel structure layer according to an embodiment of the present invention. [Figure 37] 1 is a curve of the film thickness formed in the related art. [Figure 38] 10 is a curve of the film thickness of a film formed according to an embodiment of the present invention. [Figure 39] 1 is a schematic diagram of the structure of a reflective layer in a film formation process according to an embodiment of the present invention. [Figure 40] FIG. 2 is a schematic structural diagram of a reflective layer in a film formation process according to an embodiment of the present invention. [Figure 41] 3 is a schematic structural diagram of a reflective layer in a film formation process according to an embodiment of the present invention. [Figure 42] 4 is a schematic structural diagram of a reflective layer in a film formation process according to an embodiment of the present invention. [Figure 43] 11 is a schematic structural diagram of a projection screen according to an embodiment of the present invention. [Figure 44] 12 is a structural schematic diagram of a projection screen according to an embodiment of the present invention. [Figure 45] 1 is a structural schematic diagram of a projection device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0009] To make the above-mentioned objects, features, and advantages of the present invention clearer and easier to understand, the present invention will be further described below with reference to the drawings and examples. It should be noted that the illustrated embodiments may be implemented in multiple forms and should not be understood as being limited to the embodiments described herein. Rather, providing these embodiments will make the present invention more comprehensive and complete and comprehensively convey the concept of the illustrated embodiments to those skilled in the art. Since the same reference numerals in the drawings indicate the same or similar structures, redundant description thereof will be omitted. Terms indicating positions and directions described in the present invention are all explained using the drawings as examples, but may be changed as necessary, and all such changes are intended to fall within the scope of protection of the present invention. The drawings of the present invention merely show relative positional relationships and do not represent true proportions.

[0010] With the popularity of laser display products, the market for laser TVs, which are large-screen products replacing LCD and OLED TVs, is rapidly expanding. To achieve good brightness and display effects, a projection device is generally used in combination with a projection screen.

[0011] FIG. 1 is a structural schematic diagram of a projection system according to an embodiment of the present invention.

[0012] As shown in FIG. 1, the projection system includes a projection device 2 and a projection screen 1 .

[0013] The projection screen 1 is located on the light output side of the projection device 2, and the viewer faces the projection screen 1. The projection light is emitted from the projection device 2, enters the projection screen 1, and is reflected forward through the projection screen 1, allowing the viewer to view the projected image.

[0014] Ultra-short throw projection devices have the characteristics of a short throw distance and a large projection screen, making them very suitable for home applications. The projection system according to the embodiment of the present invention can use an ultra-short throw projection device.

[0015] The projection screen used in conventional front projection systems is provided with a Fresnel structure, which has a specific tilt angle so that the light rays from the projection device can be incident on the light-reflecting material on the Fresnel structure and reflected toward the viewer, thereby allowing more of the projected light rays to be incident on the viewer's eyes.

[0016] FIG. 2 is a schematic diagram of the structure of a projection screen in the related art.

[0017] 2, the projection screen includes a surface layer 10, a Fresnel structure layer 12, and an adhesive layer 14, and the surface layer 10 and the Fresnel structure layer 12 are bonded to each other via the adhesive layer 14. The Fresnel structure layer 12 has a Fresnel structure on the side opposite to the surface layer 10, i.e., the side opposite to the viewer, with a light-reflecting material layer 13 formed on the surface. The light-reflecting material layer 13 is usually made of a light-reflecting metal such as aluminum and is formed on the surface of the Fresnel structure, so that when light enters the surface of the Fresnel structure, it is reflected by the light-reflecting material layer 13.

[0018] As shown in Figure 2, the projection light ray L emitted from the projection device enters the projection screen from the surface layer 10 side, and when it enters the Fresnel structure, it is reflected by the light-reflecting material layer 13 on the surface of the Fresnel structure and is reflected in the direction of the viewer's position.

[0019] At the same time, ambient light rays C enter the projection screen from the surface layer 10 side, and similarly, when some of the ambient light enters the light-reflecting material layer 13 on the surface of the Fresnel structure, it is reflected by the light-reflecting material layer 13 and emitted from the projection screen, and some of this reflected ambient light can enter the human eye, reducing the contrast of the projected image.

[0020] To solve the above problem, the film layer of the projection screen is usually colored, so that the colored film layer can absorb incident ambient light and reduce reflection of the ambient light.

[0021] FIG. 3 is a schematic diagram of the structure of a projection screen in the related art.

[0022] 3, the adhesive layer 14 can be colored and a light-absorbing substance such as dye or carbon black can be mixed into the material of the adhesive layer 14 so that ambient light is absorbed when it enters the adhesive layer 14. However, because the colored film layer of the projection screen absorbs light rays of all wavelengths, the output efficiency of the projected light ray L after it enters the colored film layer (e.g., adhesive layer 14) decreases, and the effect of improving contrast cannot be achieved.

[0023] In view of the above, an embodiment of the present invention provides a projection screen that can significantly improve the contrast of a projected image by selectively reflecting a wavelength band of projection light emitted from a projection device and significantly reducing the reflectance for light in other wavelength ranges.

[0024] FIG. 4 is a schematic structural diagram of a projection screen according to an embodiment of the present invention.

[0025] As shown in FIG. 4, the projection screen includes a diffusion layer 11, a Fresnel structure layer 12, and a wavelength selective reflection layer F.

[0026] The diffusion layer 11 is the outermost film layer of the projection screen and is located closest to the viewer. The diffusion layer 11 functions to diffuse light, and the projection system according to the present embodiment may use a laser light source. Because lasers have a relatively high collimation, the divergence angle of the projected light beam is relatively small. While the collimation of the light beam reflected by the projection screen is high, the viewing angle is relatively narrow. The diffusion layer 11 diverges the exit angle of the light beam passing through the diffusion layer, resulting in a consistent divergence angle of the light beam ultimately exiting the projection screen, thereby increasing the viewing angle for the viewer viewing the projected image. Additionally, the diffusion layer 11 eliminates laser speckles, contributing to the optimization of the projected image.

[0027] According to different application scenes and manufacturing processes, each Fresnel structure 121 may be a concentric circular structure arranged by sequentially expanding along the radial direction, or each Fresnel structure 121 may be a linear structure extending along the horizontal direction of the projection screen and arranged vertically to the horizontal direction, or each Fresnel structure 121 may be a periodic structure arranged in a checkerboard pattern, and the details are not limited thereto.

[0028] As shown in FIG. 4, the Fresnel structure 121 includes an inclined surface x1 and a connecting surface x2 that are connected to each other. The inclined surface x1 is inclined relative to the plane on which the diffusion layer 11 is located, and the inclination angle of the inclined surface x1 is set according to the angle of incidence and angle of reflection of the projection light. The inclination angle of the inclined surface x1 satisfies the requirement that the projection light from the projection device be reflected toward the viewer when it is incident on the surface reflection structure of the inclined surface x1. When the viewer is positioned directly in front of the projection screen, the inclined surface x1 of each Fresnel structure 121 is used to reflect the incident projection light directly forward. The connecting surface x2 is not used to reflect the projection light, but is used to connect the inclined surfaces x1.

[0029] The wavelength-selective reflective layer F is coated on at least a portion of the surface of the Fresnel structure 121 of the Fresnel structure layer 12, and is used to selectively reflect incident light. In an embodiment of the present invention, the reflectance of the wavelength-selective reflective layer F to projected light is greater than the reflectance to light in other wavelength bands. Thus, by replacing the light-reflecting material layer on the surface of the Fresnel structure 121 with the wavelength-selective reflective layer F, the wavelength-selective reflective layer F can selectively reflect projected light from a projection device, and the reflectance of light in other wavelength bands is significantly reduced. This enables a black appearance when the projection device is turned off and a bright display when the projection device is turned on, thereby significantly improving the contrast of the projected image.

[0030] As shown in Figure 4, the projection light ray L emitted from the projection device enters the projection screen from the diffusion layer 11 side, and when it enters the Fresnel structure 121, it is reflected by the surface wavelength-selective reflection layer F of the Fresnel structure, and is reflected in the direction of the viewer's position.

[0031] At the same time, ambient light C enters the projection screen from the diffusion layer 11 side, and when the ambient light C enters the wavelength-selective reflective layer F on the surface of the Fresnel structure 121, the wavelength-selective reflective layer F reflects only the projected light and has low reflectivity for light in other wavelength bands, thereby significantly reducing the reflection of ambient light and improving the contrast of the projected light.

[0032] Specifically, the wavelength-selective reflective layer F, due to the behavior of the resonant cavity, selects the wavelength of the light emitted toward the viewer, and confines other wavelength bands within the resonant cavity so that they cannot be emitted, thereby achieving the effect of selectively reflecting the incident light.

[0033] FIG. 5 is a schematic diagram of the structure of a wavelength selective reflection layer according to an embodiment of the present invention.

[0034] As shown in FIG. 5, the wavelength-selective reflecting layer F includes at least a semi-transparent layer 131, a reflecting layer 132, and a transparent medium layer 133.

[0035] The semi-transparent layer 131 is located closer to the diffusion layer 11 and is the film layer closest to the viewer in the wavelength-selective reflection layer F. The reflection layer 132 is located on the opposite side of the semi-transparent layer 131 from the diffusion layer 11 and is the film layer farthest from the viewer in the wavelength-selective reflection layer F, being spaced a certain distance from the semi-transparent layer 131. The translucent medium layer 133 is located between the semi-transparent layer 131 and the reflection layer 132 and forms a resonant cavity structure together with the semi-transparent layer 131, the reflection layer 132, and the translucent medium layer 133.

[0036] The semi-transparent layer 131, which has semi-transparency and semi-reflectivity, allows projected light rays to enter the wavelength-selective reflective layer F when they enter the projection screen, and also allows the projected light rays to exit from the semi-transparent layer 131 side after being enhanced in oscillation within the resonant cavity. The semi-transparent layer 131 may have a layered structure made of at least one metal selected from Al, Nb, Ag, Ti, etc., but is not limited thereto. The semi-transparent layer 131 may also be manufactured by methods such as sputtering and vapor deposition, but is not limited thereto.

[0037] It should be noted that the semi-transparent layer 131, which has semi-transparent and semi-reflective properties, does not necessarily have a semi-transmittance and a light reflectance of 50%. To explain that the semi-transparent layer 131 can transmit a part of the light flux and reflect a part of it, the semi-transparent layer 131 is usually set to transmit a majority or a considerable proportion of the light flux and reflect a minority or a small proportion of the light flux.

[0038] The reflective layer 132 has the function of reflecting light rays, is located on the side farther from the viewer, and does not need to transmit light rays, so it may be made of a material with or without reflectivity. The reflective layer 132 may be made of a material such as aluminum, an aluminum alloy, silver, or a silver alloy, and the thickness of the reflective layer 132 is greater than the thickness of the semi-transparent layer 131. For example, the reflective layer 132 may have a laminated structure made of an aluminum alloy such as Al or AlSi, or a silver alloy such as Ag or AgPaCu, but this is not a limitation. The reflective layer 132 may be made by a method such as sputtering or vapor deposition, but this is not a limitation.

[0039] Because the thickness of the light-transmitting medium layer 133 determines the length of the resonant cavity, the product of the refractive index and thickness of the light-transmitting medium layer 133 determines the wavelength of the light beam emitted from the resonant cavity toward the viewer and the wavelength of the light beam extinct inside the resonant cavity. Therefore, when designing the resonant cavity, it is necessary to select a dielectric material whose product of refractive index and thickness satisfies the condition for resonating the projected light beam emitted from the projection device. The light-transmitting medium layer 133 can be manufactured from materials such as metal oxides, nitrides, or transparent resins. For example, the light-transmitting medium layer 133 can be manufactured using metal oxides or nitrides such as TiO2, Nb2O5, ZrO2, Al2O3, ZnO2, or SiO2 by reactive sputtering, electron beam (EB) deposition, chemical vapor deposition, or other methods. Alternatively, the light-transmitting medium layer 133 can be manufactured using one or more laminated structures of transparent resins such as PMMA, PC, or PS by wet processes such as gravure printing or die coating. Materials are not limited to these.

[0040] FIG. 6 is a schematic structural diagram 2 of a wavelength selective reflection layer according to an embodiment of the present invention.

[0041] 6, the wavelength-selective reflecting layer F further includes a first substrate 134 located on the opposite side of the semi-transparent layer 131 from the transparent medium layer 133. The first substrate serves as a support and mounting base for the resonant cavity. In a specific implementation, the first substrate 134 may be made of a material such as polyethylene terephthalate (PET), but is not limited thereto.

[0042] The resonance behavior of the wavelength selective reflection layer will be specifically described below.

[0043] Let rH be the reflectance of the semi-transparent layer 131, tH be the transmittance, rM be the reflectance of the reflective layer 132, Ei be the electric field strength of the incident light incident on the wavelength selective reflective layer, and Er be the electric field strength of the reflected light reflected by the wavelength selective reflective layer.

[0044]

number

[0045] Here, the phase at which the resonance is maximum is

[0046]

number

[0047] Using the relationship of the resonant cavity length, it can be rewritten as follows:

[0048]

number

[0049] where:

number

number

[0050] As can be seen from the above equation, if a dielectric material with an appropriate refractive index is selected for the light-transmitting medium layer and the light-transmitting medium layer has an appropriate thickness, the reflection of the incident light beam by the resonant cavity can be enhanced.

[0051] In an embodiment of the present invention, the projection light source can be a three-color laser light source device, which can emit red, green, and blue lasers. By adjusting the refractive index and thickness of the material of the transparent medium layer, the reflection of the red, green, and blue lasers by the resonant cavity can be simultaneously enhanced, while the reflection of light rays in other wavelength bands can be attenuated, thereby improving the contrast of the projection light.

[0052] 7 shows the reflectance curves of the wavelength-selective reflective layer for light of different wavelength bands according to an embodiment of the present invention. Here, the dotted lines correspond to the central wavelengths of the red, green, and blue lasers. As can be seen from FIG. 7, the wavelength-selective reflective layer has high reflectance at the wavelengths of the red, green, and blue lasers emitted from the projection device, while significantly reducing reflectance in other wavelength bands, thereby improving the contrast of the projected light.

[0053] In specific implementations, the wavelength bands of lasers emitted by laser devices vary depending on the projection light source used. Typically, the emitted laser has a central wavelength, and the emission energy at that central wavelength is high. Furthermore, even when lasers of the same color are emitted by different laser devices, the central wavelengths are different. For example, the central wavelength of a red laser can be 635 nm, 650 nm, or 643 nm, and the central wavelength may fluctuate due to manufacturing tolerances during the production of the laser device. For example, the central wavelength of a red laser varies by ±8 nm, the central wavelength of a green laser varies between 520 nm, 525 nm, and 532 nm, and the central wavelength of a blue laser varies between 445 nm and 465 nm.

[0054] Furthermore, the refractive index and thickness of the light-transmitting medium layer of the wavelength-selective reflective layer must be designed according to the desired center wavelength of the reflected light. In the case of an ultra-short throw projection device, the distance between the projection device and the projection screen is short, so the projected light rays are incident at a large angle when they enter the projection device and the projection screen. When the projected light rays enter the wavelength-selective reflective layer at a large angle, the wavelength value of the selected reflected light rays changes. Therefore, theoretically, the narrower the wavelength band of the reflected light rays selected by the wavelength-selective reflective layer, the better. At the same time, considering compatibility with the projection light source, the center wavelength of the reflected light rays selected by the wavelength-selective reflective layer can vary within a range of 20 nm to 5 nm. The center wavelength of the reflected light rays selected by the wavelength-selective reflective layer can be 635 nm, 650 nm, or 643 nm for red light; 520 nm, 525 nm, or 532 nm for green light; or 445 nm or 465 nm for blue light, but this is not limited thereto.

[0055] FIG. 8 shows an intensity distribution curve of ambient light according to an embodiment of the present invention, and FIG. 9 shows a reflectance curve of ambient light incident on a wavelength-selective reflective layer according to an embodiment of the present invention. The intensity distribution curve of ambient light shown in FIG. 8 shows the spectral distribution of CIE standard illuminant D65. D65 corresponds to the average noonday light in Europe / Northern Europe, and is also called daylight illuminant. To demonstrate the effects of the present invention, this D65 illuminant was used as the standard illuminant in calculations.

[0056] Comparing Figures 8 and 9, we can see that the intensity of the ambient light is attenuated by approximately 45% after it hits the wavelength-selective reflective layer. Meanwhile, Figure 7 shows that the wavelength-selective reflective layer attenuates the three-color laser light by approximately 20%. Therefore, based on the attenuation rates of the projected light and the ambient light, we can determine that the intensity of the projected light is approximately 1.45 times the intensity of the ambient light ((100-20) / (100-45) = 1.45). This improves the contrast of the projected light.

[0057] Based on the above relationship of electric field strength, the power Pt of the reflected light reflected by the wavelength selective reflection layer is

number

[0058] This becomes: Here, the power of the reflected light is maximized when the sin term is 1, and minimized when the sin term is 0. Therefore, in order to improve the contrast of the projected light, the reflectance and transmittance of the semi-transparent layer can be set so that terms other than the sin term are minimized.

[0059] According to a simulation, when the central wavelength of the red laser emitted from the projection device is 643 nm, the central wavelength of the green laser is 525 nm, and the central wavelength of the blue laser is 425 nm, it is effective to set the thickness of the semi-transparent layer 131 within a range of 2 nm to 20 nm, the thickness of the reflective layer 132 to less than 100 nm, and the product of the thickness and refractive index of the transparent medium layer 133 within a range of 1200 to 1400. When the reflective layer 132 is made of a metal material, a certain thickness is necessary to achieve high reflectivity, so the thickness of the reflective layer 132 needs to be greater than 50 nm.

[0060] Figure 10 shows the relationship between the thickness of the semi-transparent layer and the ambient light intensity attenuation rate in an embodiment of the present invention. The D65 light source spectrum was used as a representative example to calculate the ambient light intensity attenuation rate. According to the inventive concept of the present invention, the higher the ambient light attenuation rate, the better the contrast.

[0061] As shown in FIG. 10, when Al is used for the semi-transparent layer 131, Al for the reflective layer 132, Nb2O5 for the transparent medium layer 133, and PET for the first base material, the thickness of the semi-transparent layer at which the attenuation rate is 40% or more is approximately 3 nm to 12 nm, and the maximum ambient light attenuation rate is obtained at a thickness of around 7 nm. Therefore, when the above structure is used for the wavelength-selective reflecting layer, the thickness of the semi-transparent layer 131 is 3 nm to 12 nm, preferably 7 nm.

[0062] Fig. 11 is a relationship curve 1 between wavelength and reflectance according to an embodiment of the present invention, Fig. 12 is a relationship curve 2 between wavelength and reflectance according to an embodiment of the present invention, and Fig. 13 is a relationship curve 3 between wavelength and reflectance according to an embodiment of the present invention. Here, Figs. 11 to 13 were all obtained by simulation when Al was used for the semi-transparent layer 131, Al for the reflective layer 132, Nb2O5 for the transparent medium layer 133, and PET for the first substrate 134, and the thickness of the reflective layer 132 was 200 nm and the thickness of the transparent medium layer 133 was a constant 609 nm. Fig. 11 shows the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 0, Fig. 12 shows the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 7 nm, and Fig. 13 shows the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 30 nm.

[0063] As shown in FIG. 11, when Al is used for the semi-transparent layer, when the thickness is 0, only reflection due to the difference in refractive index between the transparent medium layer 133 and the first substrate 134 acts, resulting in low wavelength selectivity.

[0064] 12 and 13, as the thickness of the semi-transparent layer 131 increases, the portion of the component transmitted to the resonant cavity decreases, and the portion of the component reflected by the semi-transparent layer becomes the main component. When the thickness of the semi-transparent layer 131 is 7 nm, the wavelength selection function is maximized.

[0065] Fig. 14 is a relationship curve 4 between wavelength and reflectance according to an embodiment of the present invention, Fig. 15 is a relationship curve 5 between wavelength and reflectance according to an embodiment of the present invention, and Fig. 16 is a relationship curve 6 between wavelength and reflectance according to an embodiment of the present invention. Here, Figs. 14 to 16 were all obtained by simulation when Nb was used for the semi-transparent layer 131, Al for the reflective layer 132, Nb2O5 for the transparent medium layer 133, and PET for the first substrate 134, and the thickness of the reflective layer 132 was 200 nm and the thickness of the transparent medium layer 133 was a constant 609 nm. Fig. 14 shows the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 0, Fig. 15 shows the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 15 nm, and Fig. 16 shows the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 70 nm.

[0066] As shown in FIG. 14, when Nb is used for the semi-transparent layer, when the thickness is 0, only reflection due to the difference in refractive index between the transparent medium layer 133 and the first substrate 134 acts, resulting in low wavelength selectivity.

[0067] As shown in Figures 15 and 16, as the thickness of the semi-transparent layer 131 increases, the portion of the component that is transmitted to the resonant cavity decreases. When Nb is used for the semi-transparent layer 131, unlike when Al is used, the portion of the component that is reflected by the surface of metal Nb, which has an inherently low reflectivity, becomes the main component, and the wavelength selection function is maximized at a thickness of around 15 nm.

[0068] As can be seen from the above, a change in the thickness of the semi-transparent layer 131 can cause a change in the wavelength selection function, and in specific implementation, in order to maximize the wavelength selection function, it is necessary to set an appropriate thickness of the semi-transparent layer 131 depending on the specific structure used in the wavelength selective reflecting layer F, the materials and thicknesses used in each film layer, etc.

[0069] 4, the wavelength-selective reflective layer F is coated on the inclined surface x1 of the Fresnel structure 121, and the inclination angle of the inclined surface x1 of the Fresnel structure 121 is designed according to the angle of incidence of the incident projection light. The connecting surface x2 serves to connect the inclined surface x1 and does not directly receive and reflect the projection light. Therefore, the wavelength-selective reflective layer F covers only the inclined surface x1 of the Fresnel structure and reflects the projection light that is incident on the wavelength-selective reflective layer F on the inclined surface x1 of the Fresnel structure 121. When the projection light or ambient light is incident on the connecting surface x2 of the Fresnel structure 121, the wavelength-selective reflective layer F is not provided on this surface, so that the incident light can be directly transmitted, preventing the light from being reflected from this surface and interfering with the projection light.

[0070] FIG. 17 is a schematic structural diagram of a projection screen according to an embodiment of the present invention.

[0071] In some embodiments, as shown in Figure 17, the wavelength-selective reflecting layer F is coated on the inclined surface x1 and the connecting surface x2 of the Fresnel structure 121. Analysis tests show that the wavelength-selective reflecting layer F selectively reflects different wavelengths for light rays with different incident angles.

[0072] Fig. 18 is a comparison diagram of reflectance curves at different incident angles according to an embodiment of the present invention, showing the reflectance curves of light rays of different wavelengths incident on the wavelength selective reflective layer at incident angles of 0°, 30°, and 60°, respectively.

[0073] As can be seen from Figure 18, as the angle of incidence of light incident on the wavelength-selective reflective layer changes, the wavelengths selectively reflected by the wavelength-selective reflective layer shift toward shorter wavelengths. Furthermore, the Fresnel structure of the projection screen is designed to accommodate the angle of incidence of the projection light. The ambient light incident on the projection screen comes from various directions and, after being diffused by the diffusing layer 11, enters the wavelength-selective reflective layer F at multiple angles of incidence. This portion of the light is usually multiply reflected by the surface of the wavelength-selective reflective layer. Since the angle of incidence constantly changes during the reflection process, due to the dependence of the wavelength-selective reflective layer on the angle of incidence, the ambient light can be multiply reflected by the wavelength-selective reflective layer and thereby attenuated across the entire visible light band. This significantly increases the energy ratio of the projection light among the light reflected by the projection screen, thereby improving contrast.

[0074] FIG. 19 is a third schematic structural diagram of a projection screen according to an embodiment of the present invention.

[0075] Taking the projection screen structure shown in Figure 19 as an example, the inclination angle of the inclined surface x1 of the Fresnel structure 121 is 15°, and the connecting surface x2 is perpendicular to the plane on which the projection screen is located. After an ambient light ray C enters the projection screen's outermost diffusing layer 11, it is refracted at a 25° angle, resulting in an incident angle of 65° upon the wavelength-selective reflecting layer F. This ambient light ray first enters the wavelength-selective reflecting layer on the surface of connecting surface x2, is reflected by the wavelength-selective reflecting layer on the surface of connecting surface x2, and then enters the wavelength-selective reflecting layer on the surface of reflecting surface x1. In other words, this ambient light ray is reflected twice by the wavelength-selective reflecting layer, and the incident angles upon the wavelength-selective reflecting layer twice are 65° and 10°, respectively.

[0076] FIG. 20 shows the reflectance curve of a ray of light at an incident angle of 65° by a wavelength selective reflecting layer according to an embodiment of the present invention, FIG. 21 shows the reflectance curve of a ray of light at an incident angle of 10° by a wavelength selective reflecting layer according to an embodiment of the present invention, and FIG. 22 shows the reflectance curve of a wavelength selective reflecting layer according to an embodiment of the present invention after two reflections.

[0077] As shown in Figures 20 and 21, the wavelength selective reflective layer selectively reflects light rays at incident angles of 65° and 10° at different wavelengths. The reflectance curve shown in Figure 22 can be obtained by superimposing the two reflectance curves for incident angles of 65° and 10°. As can be seen from Figure 22, ambient light rays enter the wavelength selective reflective layer at 65° and are reflected by the wavelength selective reflective layer, and then enter the wavelength selective reflective layer at 10° and are reflected by the wavelength selective reflective layer again. As a result, the reflectance of the entire visible light band is reduced to a certain extent. Therefore, when the brightness of the ambient light is strong, the intensity of the ambient light emitted from the projection screen after being reflected by the projection screen will be significantly reduced.

[0078] FIG. 23 shows a relative intensity curve of ambient light incident on a projection screen according to an embodiment of the present invention, and FIG. 24 shows a relative intensity curve of ambient light after reflection by a projection screen according to an embodiment of the present invention.

[0079] 23 and 24, when ambient light enters the projection screen at the angle of incidence shown in Fig. 19, it has high intensity in the visible light band, but after being reflected twice by the wavelength-selective reflective layer, its intensity across the entire visible light band is reduced to some extent. Because ambient light comes from various directions, it enters the projection screen at various angles. After being diffused by the diffusing layer 11 of the projection screen, the angle of incidence on the wavelength-selective reflective layer can be diversified. After the incident ambient light undergoes multiple reflections by the wavelength-selective reflective layer, the reflectance across the entire visible light band is significantly reduced, thereby attenuating the reflection of ambient light by the projection screen and improving the contrast of the projected light.

[0080] The embodiment of the present invention further provides some modified structures of the projection screen. Figure 25 is a schematic structural diagram 4 of the projection screen according to the embodiment of the present invention.

[0081] 4 and 25, the projection screen further includes an adhesive layer 14 located between the diffusion layer 11 and the Fresnel structure layer 12 to bond the diffusion layer 11 and the Fresnel structure layer 12. The adhesive layer 14 can be made of an adhesive material such as epoxy resin, acrylic resin, silica gel, or the like, but is not limited thereto.

[0082] 4, the Fresnel structure 121 of the Fresnel structure layer 12 is located on the opposite side of the adhesive layer 14, and the adhesive layer 14 is for bonding the diffusion layer 11 and the surface of the Fresnel structure layer 12 opposite to the Fresnel structure 121 to each other. When the Fresnel structure is provided on the side away from the adhesive layer 14, the semi-transparent layer of the wavelength-selective reflecting layer F needs to be provided on the side closer to the Fresnel structure 121.

[0083] 25, the Fresnel structure 121 of the Fresnel structure layer 12 is located on the side facing the adhesive layer 14, and the adhesive layer 14 is used to bond the diffusion layer 11 and the wavelength-selective reflecting layer F in the Fresnel structure 121 to each other. When the Fresnel structure is provided on the side closer to the adhesive layer 14, the semi-transparent layer in the wavelength-selective reflecting layer F needs to be provided on the side farther from the Fresnel structure 121. The order of arrangement of the film layers in the wavelength-selective reflecting layer F in FIGS. 4 and 25 is reversed.

[0084] When the Fresnel structure is provided on the side closer to the adhesive layer 14, the adhesive layer 14 acts to protect the wavelength-selective reflecting layer F. Because the Fresnel structure layer 12 is located on the side farthest from the viewer and no light rays are incident on the Fresnel structure layer 12, the specification requirements for light transmittance and damage to the Fresnel structure layer 12 are low, and it is no longer necessary to manufacture the Fresnel structure layer 12 using expensive optical materials, and it can be manufactured using relatively inexpensive industrial materials, thereby reducing production costs.

[0085] FIG. 26 is a schematic structural diagram of a projection screen according to an embodiment of the present invention.

[0086] In some embodiments, the diffusion layer 11 includes a second substrate 111 and a diffusion material 112, as shown in FIG.

[0087] A second substrate 111 , which is the substrate of a diffusion material 112 , is in contact with the adhesive layer 14 , and the diffusion material 112 is located on the surface of the second substrate 111 opposite the adhesive layer 14 .

[0088] Conventional projection systems typically use laser light sources, which have relatively high collimation, resulting in a relatively small divergence angle of the projected light beam. While the collimation of the light beam reflected by the projection screen is high, the viewing angle is relatively narrow. The addition of a diffusion layer 11 diverges the exit angle of the light beam passing through the diffusion layer, ensuring that the light beam ultimately exiting the projection screen has a consistent divergence angle, thereby increasing the viewing angle through which the viewer can observe the projected image. Additionally, the diffusion layer 11 also eliminates laser speckles, contributing to the optimization of the projected image.

[0089] The diffusion material 112 may be a resin material or an inorganic material containing diffusion particles, and the diffusion particles may be, but are not limited to, silica particles, alumina particles, titanium oxide particles, cerium oxide particles, zirconia particles, tantalum oxide particles, zinc oxide particles, magnesium fluoride particles, etc. The diffusion layer 112 may be manufactured by various coating methods, and is not limited thereto.

[0090] The second base material 111 may be made of, but is not limited to, PET, polyethylene naphthalate (abbreviated as PEN), polycarbonate (abbreviated as PC), polymethyl methacrylate (abbreviated as PMMA), triacetylcellulose (abbreviated as TAC), cycloolefin polymer (abbreviated as COP), thermoplastic polyurethane (abbreviated as TPU), polyvinyl chloride (abbreviated as PVC), polyimide (abbreviated as PI), polyamide (abbreviated as PA), polyethylene (abbreviated as PE), polypropylene (abbreviated as PP), or the like.

[0091] FIG. 27 is a schematic structural diagram of a projection screen according to an embodiment of the present invention.

[0092] 27, the diffusion layer 11 includes only a second substrate 111, which is in contact with an adhesive layer 14 and bonded to the Fresnel structure layer 12 via the adhesive layer 14. The material of the second substrate 111 includes a diffusion material, so that the first substrate 111 can have light diffusion ability and a certain haze when the second substrate 111 is formed. The second substrate 111 including the diffusion material can not only widen the viewing angle but also reduce the reflection of light rays, thereby preventing light rays from forming a clear image on the ceiling and preventing the reflection of light from the ceiling, thereby improving the viewing experience for the viewer.

[0093] FIG. 28 is a schematic structural diagram of a projection screen according to an embodiment of the present invention.

[0094] In some embodiments, as shown in FIG. 28 , the diffusion layer 11 includes only a second substrate 111, which is in contact with an adhesive layer 14 and is bonded to the Fresnel structure layer 12 via the adhesive layer 14. The surface of the second substrate 111 opposite the adhesive layer 14 is uneven. This uneven surface can be formed by sandblasting or alkali treating the surface of the second substrate 111, but is not limited thereto. The uneven surface of the second substrate 111 has a certain light diffusion effect and a matte effect, and can therefore achieve effects such as widening the viewing angle, widening the angle of incidence of incident ambient light, and preventing reflection of ceiling light.

[0095] FIG. 29 is a structural schematic diagram of a projection screen according to an embodiment of the present invention.

[0096] In some embodiments, the adhesive layer 14 may contain a light-absorbing material and be colored to improve the black brightness of the projection screen, as shown in Figure 29. In specific implementations, the adhesive layer 14 may be colored using a pigment material such as carbon black or dye to deepen the color of the adhesive layer 14, and this is not limited thereto.

[0097] FIG. 30 is a structural schematic diagram of a projection screen according to an embodiment of the present invention.

[0098] In some embodiments, as shown in FIG. 30, the projection screen may include only a Fresnel structure layer 12 and a diffusing layer 11. The Fresnel structure of the Fresnel structure layer 12 is provided on the side facing the viewer. The diffusing layer 11 is located on the surface of the wavelength-selective reflecting layer F opposite the Fresnel structure layer 12. In this case, the diffusing layer uses a diffusing material 112 coated on the wavelength-selective reflecting layer F. The diffusing material 112 can be formed on the surface of the wavelength-selective reflecting layer F by coating, spraying, or other methods. Using the projection screen structure shown in FIG. 30 can effectively reduce the thickness of the projection screen.

[0099] When a projection screen structure such as that shown in Fig. 30 is used, the semi-transparent layer in the wavelength selective reflecting layer F needs to be provided on the side away from the Fresnel structure 121. The order of arrangement of the film layers in the wavelength selective reflecting layer F in Fig. 4 and Fig. 30 is reversed.

[0100] In a specific implementation, as shown in FIG. 30, the Fresnel structure layer 12 may include a third substrate 122 whose surface facing the diffusion layer 11 and the surface opposite the diffusion layer 11 are both flat surfaces, and the Fresnel structure 121 is located on the surface on the third substrate 122 side.

[0101] The third base material 122 may be made of a material such as PET, but is not limited thereto. The Fresnel structure 121 can be manufactured by a UV molding process using a mold having a Fresnel structure and UV-curable resin. The Fresnel structure 121 can be formed by applying UV-curable resin to a mold having a Fresnel structure, and laminating and UV-curing the UV-curable resin using the third base material 122.

[0102] FIG. 31 is a structural schematic diagram of a projection screen according to an embodiment of the present invention.

[0103] 31, the Fresnel structure layer 12 may be an integral structure, in which one surface of the Fresnel structure layer 12 is a Fresnel structure 121 and the surface opposite to the Fresnel structure 121 is a flat surface. A Fresnel structure layer using an integral structure can omit the step of bonding the substrate and the Fresnel structure, further simplifying the manufacturing process.

[0104] In concrete implementation, the Fresnel structure layer 12 having an integrally molded structure can be manufactured by a thermoforming method, and the Fresnel structure layer can use a thermoplastic material, which is not limited here.

[0105] In addition, the projection screen structures shown in Figures 25 to 31 will all be described using an example in which the inclined surfaces of the Fresnel structure 121 are coated with a wavelength-selective reflecting layer F to explain the structures of other film layers, but when actually implemented, the inclined surfaces and connecting surfaces of the Fresnel structure 121 may also be coated with a wavelength-selective reflecting layer F, provided that the same other film layers are present.

[0106] FIG. 32 is a schematic structural diagram of a projection screen in the related art.

[0107] 32, in the projection screen of the related art, the reflective material layer 13 is manufactured by vapor deposition or sputtering, and the reflective material layer 13 manufactured by the conventional process usually covers the entire surface of the Fresnel structure. That is, the light-reflecting material layer 13 covers both the inclined surface x1 of the Fresnel structure and the connecting surface x2 of the Fresnel structure.

[0108] As shown in Figure 32, when ambient light rays C enter the projection screen, they are incident not only on the inclined surface x1 but also on the connecting surface x2. Some of these rays are reflected by the light-reflecting material layer 13 on the surface of the connecting surface x2 and ultimately exit the projection screen, affecting the contrast of the projected light.

[0109] In order to improve the contrast of the projected light, it is conceivable to remove the light reflecting material layer 13 on the surface of the connecting surface x2 to avoid reflection of part of the ambient light on the connecting surface.

[0110] FIG. 33 is a schematic structural diagram of a projection screen in the related art.

[0111] As shown in Figure 33, if the light-reflecting material layer 13 is not provided on the surface of the connection surface x2, the ambient light C, which would normally be reflected multiple times through the light-reflecting material layer 13 on the surface of the connection surface x2, can be emitted directly from the connection surface x2.In this way, the ambient light in this area, which would normally be reflected toward the viewer, will no longer interfere with the projected light L, and the contrast of the projected light can be improved to some extent.

[0112] However, the light-reflecting material layer on the surface of the Fresnel structure is usually manufactured using a film-forming process, and when attempting to form a film on only a part of the surface of the Fresnel structure, it is usually necessary to improve the film-forming device, which poses problems of difficulty in adjusting the device and high costs.

[0113] In view of the above, an embodiment of the present invention provides a method for manufacturing a projection screen that does not depend on a film-forming device, and that can achieve the objective of forming a film only on the connecting surfaces of a Fresnel structure and minimizing the amount of film formed on the connecting surfaces by adjusting the film-forming conditions and amount.

[0114] FIG. 34 is a flow diagram of a method for manufacturing a projection screen according to an embodiment of the present invention.

[0115] As shown in FIG. 34, the manufacturing method of the projection screen includes S10 of manufacturing a Fresnel structure layer, S20 of forming a discontinuous first thin film on the inclined surface of the Fresnel structure and forming a continuous second film layer on the first thin film, and S30 of forming a surface functional layer on one side of the Fresnel structure with a reflective layer.

[0116] In the embodiment of the present invention, the reflective layer may be formed using a single reflective material, or the reflective layer may be formed using the wavelength-selective reflective layer having wavelength selectivity, but is not limited thereto. Although the deposition method or sputtering method is still used to form the reflective layer on the Fresnel structure layer, by adjusting the deposition conditions and deposition amount, it is possible to form the light reflective layer on the inclined surface of the Fresnel structure while minimizing the deposition amount on the connecting surface.

[0117] Specifically, the Fresnel structure layer can be manufactured by a number of methods. Fig. 35 is a schematic diagram of a manufacturing flow of the Fresnel structure layer according to an embodiment of the present invention, and Fig. 36 is a schematic diagram of a manufacturing flow of the Fresnel structure layer according to an embodiment of the present invention.

[0118] In some embodiments, the Fresnel structure 121 can be formed by applying UV-curable resin to a mold M having a Fresnel structure, laminating the UV-curable resin using a substrate, and then UV-curing the resin. As shown in FIG. 35 , UV-curable resin f′ is first applied to a mold M having a Fresnel structure on its surface, and a third substrate 122 is provided. The UV-curable resin f′ on the mold M is then laminated onto the third substrate 122 with a predetermined pressure, and UV irradiation is performed from the third substrate 122 side to harden the UV-curable resin f′. As the UV-curable resin f′ hardens, it adheres to the third substrate 122, so the Fresnel shape of the mold M is transferred to the third substrate 122, forming the Fresnel structure 121 on the surface of the third substrate 122.

[0119] Fresnel structure layers formed using ultraviolet curing resins typically have separate substrates and Fresnel structures. On the other hand, Fresnel structure layers manufactured using thermoforming methods have an integrated structure, eliminating the need for a process for joining the substrate and Fresnel structure. As shown in FIG. 36 , an integrated Fresnel structure layer uses a thermoplastic material such as TPU or PVC. First, a thermoplastic third substrate 122 is provided, and a mold M having a heated Fresnel structure is used to thermoform the third substrate 122, thereby forming a Fresnel structure layer having a Fresnel structure 121.

[0120] As shown in Figures 35 and 36, the surface of the manufactured Fresnel structure layer has a plurality of Fresnel structures 121, and according to different application scenarios and manufacturing processes, each Fresnel structure 121 may form a concentric circular structure that is sequentially extended and arranged along the radial direction, or each Fresnel structure 121 may be a linear structure that extends along the horizontal direction of the projection screen and is arranged vertically to the horizontal direction, and is not limited here.

[0121] In the embodiment of the present invention, when manufacturing a reflective layer, both the film formation conditions and the amount of film formation are adjusted so that the reflective layer is formed only on the inclined surface x1 of the Fresnel structure and not on the connecting surface x2.

[0122] Specifically, embodiments of the present invention insert multiple interruption periods into the deposition process such that deposition periods alternate with interruption periods.

[0123] FIG. 37 shows a curve of the film thickness formed in the related art, and FIG. 38 shows a curve of the film thickness formed in the embodiment of the present invention.

[0124] As shown in FIG. 37, in the related art, the film formation process is continuous, and ultimately a continuous light reflecting material film is formed on both the inclined surface x1 and the connecting surface x2 of the Fresnel structure.

[0125] In contrast, in an embodiment of the present invention, as shown in Figure 38, multiple interruption periods k2 are inserted during the film formation process, so that film formation time periods k1 and interruption periods k2 alternate throughout the entire film formation process. By controlling the duration and amount of film formation of film formation time periods k1 and interruption periods k2, it is possible to first form a single discontinuous first thin film on the inclined surface x1 of the Fresnel structure, and then form a continuous second film layer on the first thin film. In this way, a continuous light-reflecting material film is formed only on the inclined surface x1 of the Fresnel structure, minimizing the amount of film formation on the connecting surface x2.

[0126] 39 to 42 are schematic diagrams showing the structure of the reflective layer in the film formation process according to the embodiment of the present invention.

[0127] Specifically, the process from no film to a continuous film in the film formation process is "nucleation → nucleus coalescence → islands → island coalescence → continuous film," and the state up to island coalescence is called a discontinuous film. Furthermore, the above film morphology is usually related to the film thickness, which is largely dependent on the film formation time, and the film formation time is related to the film formation rate.

[0128] In the embodiment of the present invention, based on the above principle, an interruption period is inserted in the film formation process and the film formation time and film formation rate are adjusted to form a single discontinuous first thin film on the inclined surface x1 of the Fresnel structure first.

[0129] As shown in Figure 39, a sharp step portion t is formed at the boundary between the inclined surface x1 and the connecting surface x2 of each Fresnel structure, so that when the amount of film formation is small, the surrounding incident atoms are suppressed, and many atoms x1 are incident on the inclined surface x1, and at the connecting surface x2, atoms x1 are incident only on a local region close to the step portion.

[0130] As shown in Figure 40, after the end of the film formation period, film formation is interrupted for a certain period of time, and the incident atoms become stable nuclei b. The presence of the step portion t suppresses the atoms from moving around the connection surface x2, and as a result, the inclined surface x1 is formed preferentially on the discontinuous first thin film s1.

[0131] As shown in Figure 41, after the interruption period ends, film formation continues on the Fresnel structure, and the atoms a2 that are incident at this time are deposited around the atomic nuclei that were formed earlier, and since the area around the position with the first thin film s1 becomes higher, film formation proceeds preferentially over other positions.

[0132] As shown in FIG. 42, after multiple deposition periods have been accumulated, the thin film continues to grow until there are no more nuclei preferentially forming on the inclined surface x1, resulting in a continuous second film layer s2 across the entire inclined surface.

[0133] In practice, the interruption period k2 is set longer than the film formation time period k1, and the longer the interruption period k2, the better the effect. Considering practical operability, the length of the interruption period k2 can be set to 30 to 60 seconds, and the length of the film formation time period can be set to 1 to 10 seconds (for example, about 5 seconds).

[0134] In this way, a reflective layer is formed on the inclined surface of each Fresnel structure in the Fresnel structure layer, and after obtaining a Fresnel structure layer having a light-reflecting layer on its surface, a surface functional layer can be formed on the surface opposite the Fresnel structure layer.

[0135] The surface functional layer is usually located on the outermost surface of the projection screen, and in the embodiments of the present invention, the surface functional layer can be subjected to different treatments according to different needs to achieve effects such as widening the viewing angle, preventing reflection of ambient light, preventing reflection of ceiling light, etc. The manufacturing method of the surface functional layer may include adhesion, spraying, etching, etc., and is selected according to the type of surface functional layer, and is not limited here.

[0136] In some embodiments, the wavelength selective reflecting layer F in the above embodiments can be used as the reflecting layer, and the diffusion layer 11 in the above embodiments can be used as the surface functional layer.

[0137] When the wavelength-selective reflecting layer F is used as the reflecting layer, the wavelength-selective reflecting layer includes a laminated semi-transparent layer 131, a transparent medium layer 133, and a reflective layer 132. To form the wavelength-selective reflecting layer only on the inclined surface x1 of the Fresnel structure, any of the film layers of the wavelength-selective reflecting layer (the semi-transparent layer 131, the transparent medium layer 133, and the reflective layer 132) can be manufactured using the discontinuous film formation process described above. Film layers manufactured using the discontinuous film formation process first form a discontinuous first thin film, and then form a continuous second film layer on the first thin film. The first thin film and the second film layer can be manufactured using the same or different materials as needed. If the first thin film and the second film layer are manufactured using the same material, the final film layer will have no clear boundary, and a continuous film layer will be formed only on the inclined surface of the Fresnel structure.

[0138] For example, when the reflective layer 132 in the wavelength-selective reflective layer is manufactured by the discontinuous film formation process, the discontinuous thin film generally has a thickness of 1 nm to 10 nm when converted into a film thickness, and therefore the thickness of the first thin film s1 formed in the reflective layer 132 is 1 nm to 10 nm. The second film layer is required to have good light reflectivity, and in the embodiment of the present invention, the thickness of the second film layer s2 in the reflective layer 132 is 50 nm to 200 nm, and the thickness of the second film layer s2 is usually kept to 500 nm or less to avoid the reflective film becoming excessively thick.

[0139] The first thin film s1 is formed first so that subsequent films grow preferentially on the inclined surface. Furthermore, the first thin film s1 is a relatively thin, discontinuous film with no reflectivity. Therefore, the first thin film s1 can be made of a metal material or a transparent dielectric material. Metal materials include Ag or Al, and transparent dielectric materials include Al2O3, Nb2O5, TiO2, ITO, SiO2, and the like, but are not limited thereto.

[0140] The second film layer s2 on the first thin film s1 is intended to reflect incident light rays, and therefore can be made using a reflective metal material, such as Ag or Al, but is not limited thereto.

[0141] Similarly, the semi-transparent layer 131 and the transparent medium layer 133 in the wavelength-selective reflecting layer F can also be manufactured by the above-mentioned discontinuous film formation process, and the film can be formed only on the inclined surface x1 of the Fresnel structure, minimizing the amount of film formed on the connecting surface x2.

[0142] In particular, the light-transmitting medium layer in the wavelength-selective reflection layer F is made of a light-transmitting material, and therefore has only light-transmitting properties when formed on the inclined surface x1 and the connecting surface x2 of the Fresnel structure. Because these light-transmitting film layers do not interfere with light even when formed on the connecting surface x2, these completely light-transmitting film layers can also be manufactured using conventional film-forming processes, and are not limited to these processes. Typically, to reduce material costs, they are manufactured using a discontinuous film-forming process.

[0143] Furthermore, in a specific embodiment, the Fresnel structure first forms a semi-transparent layer 131, and then sequentially forms the transparent medium layer 133 and the reflective layer 132 on the semi-transparent layer 131. The semi-transparent layer 131 can be formed by a discontinuous film formation process, and then sequentially forming the transparent medium layer 133 and the reflective layer 132 by a discontinuous film formation process. However, because the semi-transparent layer 131 transmits most of the light beam and reflects a small portion of the light beam, the semi-transparent layer 131 can also be formed by a conventional overall film formation process, and then sequentially forming the transparent medium layer 133 and the reflective layer 132 by a discontinuous film formation process.

[0144] Even in a structure in which the reflective layer is made only of a light-reflecting material, the reflective layer can be manufactured by a discontinuous film formation process. Specifically, a first thin film s1 of 1 nm to 10 nm is first formed on the inclined surface x1 of the Fresnel structure, and then a second film layer s2 of 50 nm to 200 nm is formed on the first thin film s1.

[0145] Based on the same inventive idea, an embodiment of the present invention further provides a projection screen manufactured by any of the above manufacturing methods. Figure 43 is a structural schematic diagram of a projection screen according to an embodiment of the present invention.

[0146] As shown in FIG. 43, the projection screen includes a surface functional layer 11', a Fresnel structure layer 12 and a reflective layer 13'.

[0147] The surface functional layer 11' is located on the outermost surface of the projection screen, and in the present embodiment, the surface functional layer 11' is located on the side closest to the viewer. In addition to protecting the projection screen, the surface functional layer 11' can also be processed by various means according to different needs to achieve effects such as widening the viewing angle, preventing reflection of ambient light, preventing reflection of ceiling light, etc. In some embodiments, the surface functional layer 11' can use the above-mentioned diffusion layer 11.

[0148] The Fresnel structure layer 12 is located on one side of the surface functional layer 11', specifically, on the opposite side of the surface functional layer 11' from the viewer. The surface of the Fresnel structure layer 12 is provided with Fresnel structures 121 distributed according to a predetermined rule, and the Fresnel structures 121 have inclined surfaces x1 and connecting surfaces x2 that are connected to each other.

[0149] The reflective layer 13′ is located on the inclined surface x1 of each Fresnel structure 121. The reflective layer 13′ according to the embodiment of the present invention is manufactured by a deposition process such as evaporation or sputtering, and the used apparatus is an evaporation apparatus or sputtering apparatus that is well-established in the related art. There is no need to improve the deposition apparatus. By adjusting the deposition conditions and deposition amount and using a discontinuous deposition process, the reflective layer can be formed on the inclined surface of the Fresnel structure, and the deposition amount on the connecting surface can be minimized, thereby avoiding the problems of difficulty in adjusting the apparatus and high costs.

[0150] In some embodiments, the reflective layer 13' is a light-reflective material layer 13 in the related art.

[0151] In some embodiments, the reflective layer 13' can be the wavelength-selective reflective layer F according to the above embodiments.

[0152] In addition, any of the layers of the reflective layer 13' can be formed by a discontinuous thin film process. In the current manufacturing process, a discontinuous first thin film s1 located on the inclined surface of the Fresnel structure and a second thin film s2 located on the first thin film s1 are formed.

[0153] In the projection screen according to the embodiment of the present invention, a reflective layer is provided only on the inclined surface of the Fresnel structure, so that the ambient light incident on the connecting surface can be directly emitted from the connecting surface. In this way, the ambient light from this portion that would normally be reflected toward the viewer does not interfere with the projected light, thereby improving the contrast of the projected light to a certain extent.

[0154] FIG. 44 is a structural schematic diagram of a projection screen according to an embodiment of the present invention.

[0155] 44, a light-absorbing layer 15 may be provided on the Fresnel structure layer 12 on the side opposite the surface functional layer 11'. The light-absorbing layer can absorb light emitted from the connecting surface x2 of the Fresnel structure, preventing this light from re-entering the projection screen due to reflection or other effects. The light-absorbing layer 15 can be realized by doping the film layer with a light-absorbing material. For example, the film layer material can be colored by adding carbon black or a dye to it so that it has the effect of absorbing light, but this is not limited thereto.

[0156] The projection screen according to the embodiment of the present invention further includes an adhesive layer. The position of the adhesive layer and the modified structure of the projection screen can be referred to in the above embodiment, so the description thereof will be omitted here.

[0157] An embodiment of the invention further provides a projection system, as shown in FIG. 1, which comprises a projection device 2 and a projection screen 1 .

[0158] FIG. 45 is a schematic structural diagram of a projection device according to an embodiment of the present invention.

[0159] 45, the projection device includes a light source device 21, an illumination light path 22, a light modulation member 23, and a projection lens 24. Here, the illumination light path 22 is located on the light output side of the light source device 21, the light modulation member 23 is located on the light output side of the illumination light path 22, and the projection lens 24 is located on the light output side of the light modulation member 23.

[0160] The light source device 21 can be a laser light source device. The laser light source device can be a monochromatic laser device, a laser device capable of emitting laser light of multiple colors, or multiple laser devices emitting laser light of different colors. When a monochromatic laser device is used in the laser light source device, a color wheel for color conversion must be further provided in the laser display device, and the monochromatic laser device can achieve the purpose of emitting primary color light of different colors in time sequence in accordance with the color wheel. When a laser device capable of emitting laser light of multiple colors is used in the laser light source device, the laser light source must be controlled to emit laser light of different colors in time sequence to form primary color light.

[0161] In an embodiment of the present invention, the light source device may be a three-color laser light source device, which may be a laser device that emits three primary color laser beams, such as an MCL laser device, or may include a red laser device, a green laser device, and a blue laser device that respectively emit the three primary color laser beams. The use of a three-color laser light source device contributes to improving the color gamut of the projected image, providing better color expression and enabling the input image to be accurately reproduced.

[0162] The illumination light path 22 located on the light output side of the light source device 21 collimates the light emitted from the light source device 21, while allowing the light emitted from the light source device 21 to be incident at an appropriate angle on the light modulation member 23. The illumination light path 22 may include a plurality of lenses or a lens group, and is not limited thereto.

[0163] The light modulation element 23 modulates the incident light beam. In a specific implementation, the light modulation element 23 can be a digital micromirror device (abbreviated as DMD). After the light beam passes through the illumination light path 22, it meets the illumination size and incident angle required for the DMD. The surface of the DMD is provided with a plurality of micro-reflection mirrors, each of which can be independently driven and deflected. Controlling the deflection angle of the DMD controls the brightness of the light beam incident on the projection lens 24.

[0164] The projection lens 24 is for forming an image from the light emitted from the light modulation member 23, and after forming an image by the projection lens 24, the formed image is projected.

[0165] In an embodiment of the present invention, the projection device 2 can be an ultra-short throw projection device, i.e., the projection lens 24 in the projection device is an ultra-short throw projection lens. By using an ultra-short throw projection device, the distance between the projection device 2 and the projection screen 1 can be significantly shortened, thereby shortening the projection distance and realizing a large-screen image display.

[0166] The projection screen 1 is located on the light output side of the projection lens of the projection device. The projection screen 1 includes a surface functional layer, a Fresnel structure layer, and a wavelength-selective reflective layer located on at least a portion of the surface of the Fresnel structure of the Fresnel structure layer. The wavelength-selective reflective layer selectively reflects light projected from the projection device while significantly reducing the reflectance of light in other wavelength bands, enabling a black appearance when the projection device is turned off and a bright display when the projection device is turned on, thereby significantly improving the contrast of the projected image.

[0167] Although preferred embodiments of the present invention have been described above, those skilled in the art will be able to make other changes and modifications to these embodiments once they have acquired the basic creative concept. Therefore, the appended claims are intended to cover the preferred embodiments and all such changes and modifications that fall within the scope of the present invention.

[0168] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations. [Explanation of symbols]

[0169] 1-Projection screen 2-Projection device 10-Surface layer 11-Diffusion layer 11'-Surface functional layer 111-Second substrate 112-Diffusion Materials 12-Fresnel structure layer 121-Fresnel structure x1-slope x2-Connection surface 122-Third Substrate 13-Light reflective material layer 13'-reflective layer 14-adhesive layer F-wavelength selective reflective layer 131-Semi-transparent layer 132-Reflective layer 133-Transparent medium layer 134-First substrate 21-Light source device 22-Illumination light path 23-Light modulation components 24-projection lens s1 - first thin film s2 - second membrane layer f'-UV curing resin M-mold C-Environmental rays L-projection ray

Claims

1. A projection screen, A diffusion layer; a Fresnel structure layer located on one side of the diffusion layer and having a Fresnel structure on a surface of the one side; a wavelength-selective reflective layer that is coated on at least a portion of the surface of the Fresnel structure of the Fresnel structure layer and has a higher reflectivity for projection light emitted from a projection device than for light in other wavelength bands.

2. the Fresnel structure includes an inclined surface and a connecting surface that are connected to each other; the inclined surface is provided so as to be inclined with respect to a plane on which the diffusion layer is located, and an inclination angle of the inclined surface satisfies the requirement that the projection light of the wavelength selective reflection layer incident on the surface of the inclined surface is reflected toward a viewer; The projection screen according to claim 1 , wherein the wavelength-selective reflective layer is coated on the surface of the inclined plane of the Fresnel structure.

3. the Fresnel structure includes an inclined surface and a connecting surface that are connected to each other; the inclined surface is provided so as to be inclined with respect to a plane on which the diffusion layer is located, and an inclination angle of the inclined surface satisfies the requirement that the projection light of the wavelength selective reflection layer incident on the surface of the inclined surface is reflected toward a viewer; The projection screen according to claim 1 , wherein the wavelength-selective reflective layer is coated on the surfaces of the inclined surface and the connecting surface of the Fresnel structure.

4. The wavelength selective reflective layer is a semi-transparent layer located closer to the diffusion layer; a reflective layer located on the opposite side of the semi-transparent layer to the diffusing layer; a light-transmitting medium layer located between the semi-transmitting layer and the reflective layer, 4. The projection screen according to claim 1, wherein the product of the refractive index and the thickness of the light-transmitting medium layer satisfies a condition for resonating light emitted from the projection device.

5. the semi-transparent layer has a laminated structure made of at least one metal selected from the group consisting of aluminum, niobium, silver, and titanium; 5. The projection screen according to claim 4, wherein the semi-transparent layer has a thickness of 2 nm to 20 nm.

6. The reflective layer is made of aluminum, an aluminum alloy, silver, or a silver alloy, 5. The projection screen of claim 4, wherein the thickness of the reflective layer is greater than 50 nm and less than 100 nm.

7. 5. The projection screen according to claim 4, wherein the light-transmitting medium layer is made of a metal oxide, a nitride, or a transparent resin.

8. The material of the light-transmitting medium layer is TiO ２ , Nb ２ O ５ , ZrO ２ , Al ２ O ３ , ZnO ２ and SiO ２ 8. The projection screen according to claim 7, wherein at least one of the following is used.

9. 8. The projection screen of claim 7, wherein the product of the thickness of the light-transmitting medium layer and the thickness of the light-transmitting medium layer is 1200 to 1400, and the wavelength-selective reflective layer simultaneously reflects red laser, green laser, and blue laser emitted from the projection device.

10. 10. The projection screen according to claim 9, wherein the center wavelength of the light reflected by the wavelength-selective reflective layer varies within a range of 5 nm to 20 nm.

11. 11. The projection screen of claim 10, wherein the wavelength selective reflection layer reflects a red laser having a central wavelength of 635 nm, 650 nm, or 643 nm, a green laser having a central wavelength of 520 nm, 525 nm, or 532 nm, and a blue laser having a central wavelength of 445 nm or 465 nm.

12. 12. The projection screen according to claim 4, wherein the wavelength-selective reflective layer further comprises a first substrate located on the opposite side of the semi-transparent layer from the light-transmitting medium layer.

13. an adhesive layer positioned between the diffusion layer and the Fresnel structure layer; the Fresnel structure of the Fresnel structure layer is located on an opposite side of the adhesive layer, and the adhesive layer is configured to bond the diffusing layer and a surface of the Fresnel structure layer opposite the Fresnel structure to each other; Alternatively, the Fresnel structure of the Fresnel structure layer is located on a side facing the adhesive layer, and the adhesive layer is configured to bond the diffusion layer and the wavelength-selective reflection layer in the Fresnel structure to each other, 13. The projection screen of claim 1, wherein the adhesive layer comprises a light-absorbing material.

14. the Fresnel structure layer is located on a side facing a viewer, and the diffusing layer is located on a surface of the wavelength selective reflecting layer opposite to the Fresnel structure layer; 13. The projection screen according to claim 1, wherein the diffusion layer is a diffusion material coated on the wavelength-selective reflection layer.

15. the Fresnel structure layer includes a third substrate, the surface of which facing the diffusion layer and the surface of which opposite to the diffusion layer are both flat surfaces, and the Fresnel structure is located on the surface of the third substrate; Alternatively, the Fresnel structure layer has an integral structure, one surface of the Fresnel structure layer has a Fresnel structure, and the surface of the Fresnel structure layer opposite to the Fresnel structure is a flat surface.

16. A method for manufacturing a projection screen, comprising: a manufacturing process of a Fresnel structure, which comprises manufacturing a Fresnel structure layer, and having a plurality of Fresnel structures on one side of the Fresnel structure layer, the Fresnel structures having inclined surfaces and connecting surfaces connected to each other; a manufacturing step of a reflective layer, which comprises forming a discontinuous first thin film on the inclined surface of the Fresnel structure and forming a continuous second film layer on the first thin film; and a surface functional layer manufacturing step of forming a surface functional layer on one side of the Fresnel structure layer with the reflective layer.

17. The manufacturing process of the reflective layer uses a vapor deposition or sputtering process, The manufacturing process of the reflective layer includes: Inserting a plurality of interruption periods in the deposition process so that deposition periods and interruption periods alternate; 17. The method for manufacturing a projection screen according to claim 16, wherein the duration of the interruption period is longer than the duration of the film formation time period, the duration of the interruption period being 30 seconds to 60 seconds, and the duration of the film formation time period being 1 second to 10 seconds.

18. the reflective layer is a wavelength-selective reflective layer, The wavelength selective reflective layer is a semi-transparent layer located closer to the surface functional layer; a reflective layer located on the opposite side of the semi-transparent layer to the surface functional layer; a light-transmitting medium layer located between the semi-transmitting layer and the reflective layer, the product of the refractive index and the thickness of the light-transmitting medium layer satisfies the condition for resonating the projected light beam from the projection device; 18. The method for manufacturing a projection screen according to claim 16, wherein any one of the film layers in the wavelength-selective reflective layer is manufactured in a manufacturing process for the reflective layer.

19. a first thin film in the reflective layer using a metal material or a transparent dielectric material, and a second film layer in the reflective layer using a metal material; 19. The method for manufacturing a projection screen according to claim 18, wherein the first thin film has a thickness of 1 nm to 10 nm, and the second film layer has a thickness of 50 nm to 200 nm.

20. 1. A projection system comprising: a projection device for emitting projection light rays; and a projection screen located on the light-emitting side of the projection device, wherein the projection screen is the projection screen according to any one of claims 1 to 15, The projection device is an ultra-short focus laser projection device, and the projection device is a three-color laser light source device for emitting three primary color laser beams; a light modulation member located on the light output side of the three-color laser light source device, for modulating the laser light output from the three-color laser light source device; a projection lens located on the light output side of the light modulation member.

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